This is an extremely difficult piece to write for many reasons, not least because of my own views. This is an area where no one is an expert and the text below is less a guide and more of a thought process.
Many people have no idea what to do if someone is suicidal. Its rare that people talk about suicide though its not rare to want to die or think how to kill themself.
I'm lucky because I've been through a few suicide attempts over the years (that must be one of the strangest sentences I've ever written...). Wanting to die is normal for me and has been for the majority of the past few years. I have the lived experience of the things that have worked and the huge barriers.
For me the first thing for someone who is suicidal to know that they shouldn't go through it alone. I'm not sure I can think of a greater hell except psychosis/ego death itself. Ensuring they have someone they can always go to no matter what is vital because often its those closest to the person that the person will not talk about their deathwishes to, for obvious reasons.
My personal view is that I won't directly talk someone out of doing anything. I won't criticise their desire to die. I won't help them but I won't condone them and I'll allow them to speak about it as if it was the weather. That's really important I feel because many people won't talk about it for many reasons and those that do really don't want to be told not to do it. That's the natural reaction though and its one that I've always listen to with a polite smile and ignored. Its what I expect that person's friends and loved ones to say like a mental health key message so I don't need to say and frankly I think I'd be a liar if I said it.
My amorality aside, it means a suicidal person will keep talking to me when they won't talk to anyone else about it. It means that person always has someone they can talk to no matter how bad the situation, no matter how worthless or hopeless they feel, no matter what they're thinking of doing. This is absolutely essential because I've noticed in my own life the pattern where the reduction in social contact can quickly lead to thinking about suicide to planning or actual attempts. There are many examples of people being saved from suicide by the random kindness or interaction of strangers or friends. I'll admit that to some people I have explicitly said, "if you're going to do it please give me a call and I'll join you." which sounds horrific but I can say it with a degree of honesty and it means that, perhaps, they maybe they'll take up that offer of a last contact before they go.
The value of my personal experience of the hells of life and my openness means that I have a certain credibility or authority that might make the words, "it'll get better" or "its not always like this" have a fractionally chance of actually getting through to a person who can't see that to be possibly true. Getting a chink of hope into a person's mind is vital. Often its unending and pure hopelessness that drives people to kill themselves. Its not easy though and done badly it may distance the suicidal person from talking about it again with that person.
In my personal experience many people feel like they want to die on a regular basis but never, ever mention it and they can be the happiest person on the outside. This state can change and become a very, very dark place and this can happen without warning. In this dark place the nature of the individual's relationship with those suicidal thoughts is different. In the mild state it can be a useful coping mechanism to dispel life's problems and it a thought that can be pushed away. In the dark place its not so simple. It can be all pervading and the solution of ending things becomes a reasonable, practical way to end the hopelessness. (Even as I write now I can feel the tug of desire for the peacefulness of eternal slumber.) They can rationalise the social effect of suicide or simply hate themselves more to get past the effects on friends and family, or it may be something they don't consider because their minds have become inward focused.
Herein lies the value of trying to get the that tiny, teeny sense of hope. In my mind I see it as a thin, barely perceptible ray of light breaking into a darkened room. But it is the tiny difference between the pitch black that the mind can not handle and the black it can see. The pitch black analogy is experienced by people who use a photographic darkroom for the first time as their mind tries to adjust to the total blackness they have never experienced before even on the darkest, cloudiest nights. Everywhere outside the darkroom there is a small, sometimes imperceptible amount of light that the mind requires to 'see' black. In the darkroom the mind is out of its depth.
Some forms of suicide are about loss of hope but there are other reasons and its important to understand that a person may not reveal their true reasons and those reasons may not fit a generalisable picture. But the offering of hope that the situation can change I think can get through.
The problem is that its the obvious thing to say and that 'intelligent' (whatever that means) people know that there is hope even when they feel hopeless. Its the thought that may or may not get said. "Yes, I know there's hope but I don't feel it now and my present state is wanting to end it, so fuck off with your positive attitude."
An alternative can use distraction, fun and whatever else to indirectly work with the individual. I'm always in the pub and its an excellent environment to deal with someone who is suicidial if there is a suitably secluded spot away from prying ears. There are antidepressant-depressants available on tap and these also help people to open up. I. The environment is socially safe and it is a place that many people have fond memories of. Alcohol loosens people up, relieves stress and makes people happier when they're drunk and its a widely accept social medication. The hangover is the ideal form of depression - the cause is easily identified as a consequence of the night before. There is the risk of recklessness induced by alcohol and redoubled by recklessness behaviour induced by suicide (not wanting to live can change a person's attitudes to risk) leading to a drunken attempt. Its important to note that risk.
What I'm saying is a couple of pints and a chat can, perhaps, do more than seeing a professional who the suicidal person knows is going to try and talk them out of it and psychiatric antidepressant medication which is also given to stop them killing themselves. Its important that the chat isn't about suicide unless the person wants to talk about it. Maintaining social contact, distraction and ensuring that there is a bit of fun is the important aspect in my opinion. They are natural, temporary ways to relieve suicidal thoughts. Even if the suicidal person is smiling and laughing but still crying on the inside the effect of them pretending to smile and laugh can have the effect of making them genuinely express that way. That memory of simple fun can wake up that bit of a person's psyche that says, "well I like having fun. At least I can keep on doing that" or whatever other inner thought process happens such that a person moves out of the dark.
Engaging in a conversation about suicide is very difficult for anyone who is not an experienced professional or someone without extensive lived experience. For the inexperienced listening is the key and allowing the person the opportunity to accept they are suffering may also be important (many don't understand the significance of the distress that brought them to the point of suicide). Also getting them to talk more is useful because it can be a way for them to offload and in my opinion I think it is an effective way of reducing their suicidality in the short term.
Experienced people can have a more meaningful conversation. I'm not sure I'm capable of elucidating on how this would go but I'm making a differentiation between the experience levels of the samaritan because an inexperienced person can be treading in murky territory and it can be bad for their mental health if they feel like they've said the wrong thing and the person ends up killing themself. The best way to avoid that future guilt is to tread lightly.
I feel experienced people can take a different approach because they realise that often there's nothing positive or negative another person can do directly for someone who is truly suicidal (I'm making a distinction but one that I feel doesn't need explanation). They may also be more capable of taking the risks in communication and conversation necessary to get that person to listen to even a small amount of what is said, so they may be able to confront the issue that the person wants to kill themself about rather than side step it for safety.
Confidentiality is vital though I'm aware that it my case confidentiality has been broken. I've accepted that but other people wouldn't and it can be deleterious to a personal relationship. Revealing suicidal ideation is a massive step for someone. Breaking that trust can be catastrophic. Many people may want to talk to that person's close friends or their family or loved ones about it but my opinion is that it is up to that individual. The worst thing anyone can do is make the foolish mistake (as has been done to me in the past) of contacting mental health services who's knee-jerk reaction is far too often hospitalisation.
This is a very, very, very tricky area and my opinion is only that. I'm sure other people will make their own decisions but the loss of trust can be something that can be catastrophic to a distressed individual. There is little that mental health services can do except section and from personal experience that makes things worse. It is better to discuss your intention with the individual and if they firmly say "no" then it see if they will speak to someone anonymously or speak to the Samaritans helpline or speak to a person with lived experience or professional expertise outside the NHS system.
I strongly value suicide survivors in helping the suicidal because they are able to give real personal accounts. A survivor's life is usually full of useful tales that can help the newly suicidal see that they're not alone and they're not abnormal, that life can be strange and that their suicidal desire will go away. For those without that 'gift' and curse dealing with someone who is suicidal feels very out of their depth I would guess.
As a surivor there's something I can say with confidence (at this present time). Its gets better and there's hope. Those messages are much better coming from someone know to have been in the same dark place in their past that the suicidal person is in their present. Its perhaps why ending up in a psychiatric ward can be a good thing (though this is not part of the design of that system). Being able to speak to other veterans of suicidal ideation is better than speaking to any mental health professional.
I want to end on an important thing to remember as a conclusion and the important thing I can think of is to recognise the difficulty and the unending futility before engaging with someone who is suicidal. It is very hard for most people and the rewards are often not seen directly except in their continued existence. When I've been suicidal and talking about it there have been times when I've been an arsehole and that's why I'm making this point. Its an important point because it will help the samaritan through the difficulty so they can help the suicidal more.