1. Listen to them
They feel lost. Things that used to cause them enjoyment seem insignificant to them. Listen to them talk about it. Yes, it may be a "depressing conversation", but they need people to listen. They need away to let their feelings out in a non self destructive way. They need someone to listen and to try to understand that isn't their therapist.
2. Be there.
Whether you're studying beside them in silence, gossiping about whatever else is going on, helping them make a life plan, or lending a shoulder to cry on, just be there. Meet them after class with a coffee. Sometimes they just need someone in the same room to remind them that they aren't alone. Let them hermit when they need to, but be a constant reminder that someone loves them, someone understands them, and that someone genuinely wants to be around them.
3. Invite them out
No matter how many times they say no, keep on inviting them out. It feels worse to not be invited than to say no. Encourage them to partake in things you do to help your mental health. Walk to starbucks to get fresh air, go to the gym to get endorphins, take them out to lunch. Hygiene, exercise and nutrition tend to disappear when one is feeling suicidal, so partaking in activities that encourage these with them is a great way to get outside, help them, and also help yourself.
4. Accept that you aren't in control
You can't always be there. You need to sleep, you have appointments, you have school or work. You can't control what your friend does or think. You can help. You can reinforce positive thoughts and encourage them to get help, but at the end of the day it is their decision. Do not pressure them into making empty promises or to get treatment they aren't ready for. Leave that for medical professionals. It's upsetting to say, but if you have a suicidal friend, they might attempt, and it might be successful. It is not your fault. It is not their fault. It is depression's fault. Do what you can't but accept that you can't fix the situation.
5. Have the tough conversations
If they're on meds, should their meds be in their room? This is more applicable if you live with your friend, but should you be holding on to their meds. Are there any signs you should look out for, and what should you do to help if you notice these signs? Ask them if they're getting help. It isn't your job to make them get help, but have your friend be honest with you as to what steps they're taking.
6. Make the tough decisions
Is your friend completely uncontrollable and you're worried about their safety? If you know that they need to go to the hospital, you need to make the decision to call the paramedics or the police. If you feel comfortable taking them, then take them. Did you find your friend passed out beside a bottle of pills, or asleep and bleeding? Call 911. They might hate you for a bit. But they'll thank you after, and understand why you did it.
7. Take care of yourself
It's not your job to take them. It's your job to take care of you. If you're texting each other but you need to go to bed, let them know they can keep on talking to you and you'll read the messages in the morning. If you can't visit them in the hospital because of bad hospital anxiety, call them. If they're triggering your mental illness, let them know gently, and steer the conversation in an other direction. Feed yourself. Sleep. Go to the gym. You're friend will get better.