A couple things picked up being around addicts of substances.
The first thing they tell you about trying to stop a behavior you no longer want in your life is to stop kicking yourself if you fuck up. It might sound counterintuitive, but hitting yourself for fapping is going to make you feel worse, more stressed, etc. and you're going to want to relieve that pain with fapping or what have you.
Second, you're gonna fuck up, that's part of recovery. That's fine, most everybody does it, you're not a failure. Try to focus on the time you felt better when you didn't fap from how bad you feel relatively when you do. If you can't do that, again that's fine. It's really more about self love than jacking off here. Addiction is a very illogical behavior to undertake in the first place. You have to make your life better or you're just going to go back to fapping. You can't force yourself not to do it.
Third, you pretty much have to make your life overall better. Just think of it as another vice you'd like to kick out of your life to better yourself. It's not altogether a bad one, considering there are far worse out there, but that's kind of beside the point. That being said, see if you can't do some pushups or go for a run or try to connect with God or meditate a bit, for example. Usually there's something else bothering you that leads you back to relapsing, although just sitting around waiting for it to smack you over the head with its obviousness isn't likely going to help you find out what it is. Try to make whatever you want to replace it with both constructive and fun. I can almost guarantee that if you get into the habit of running for a while you're going to hate missing your next one. Lots of addicts like to replace their addictions to substances with exercise.
Fourth, get away from porn sites, know where the temptations are, and avoid going there if you can, it's just a slippery slope. If you can't avoid /mlpol/ then don't click on horsepron threads if you're into that. Try to appreciate the feminine form as a work of God's art than use it as your smut like a coombrain would. You are not a coombrain, you are Überhengst.
And fifth, and this has been alluded to earlier, just try it. You can always go back to fapping later. People tell you not to do it because they say it makes you ascend, try it and see for yourself. If you do, and then fuck up later, you have that positive memory of nofap to look forward to again for your next streak. Girls will take notice in the change in your behavior, and flirting with them with ease is better and has longer lasting beneficial effects than rubbing one out.
You are the only one that can keep yourself from fapping. While support from frens might help here and there, it's really about the self-control that you can impose. That being said, best of luck and Godspeed.