Talk to others about your feelings. Tell a friend or a family member. If it's bad get professional help. Do things you like to do. Take care of your physical health (even a 15 min. walk can do wonders when you're down). Personally, I suffer from bipolar disorder. When I'm suicidal, I tend to think the whole world would be better off without me and I can't think clearly. However, my friend once told me that if I committed suicide she would kill me. That thought, that makes no sense, tends to be what I need the most when I can't think rational. I get reminded that people care and would be sad if I'm not there.
Ive been there too. I dont know if it will work for you but for me i imagined that if i killed myself, imagine what other people would say or call my parents and siblings. Like if they see my sisters i imagined that people would say "her sister committed suicide" or would say to my parents "they probably didnt care about her". I didnt want people to talk bad about the people i'll be leaving behind. And i didnt want my family to think that they were at fault. I though if i was gonna die i dont want to cause harm to the people i love (which i thought was impossible cuz they will probably get hurt).
I also got myself some new hobbies like collecting stuff, just something that makes me happy.
Also, have things to look forward to. It can be as simple as a new chapter from the manga or anime you're into. Make plans like traveling and meeting friends. For me i made sure that i at least have a scheduled travel/hike/beach escaped/etc per month.
And i started making a list called "what is happines" list. I basically write anything that made me happy that day. It could be a 1 liner, or a whole page of paper. And when im sad or feeling lost again, i look at my collection and my happiness list.
And pray. Ask the Lord to not let go of you. When i'm down in the dumps i say a little prayer "Lord, hold on to me. Dont let me go"
It worked wonders for me. I hope it works for you to.
I'm also suicidal hahahaha sometimes I can control my thoughts and thinks of things I would like to do alive, the updates I've been waiting, however sometimes Im willing to let go of alll those things just to end every. I don't know how to get this suicidal thoughts away.