I know that for ■■■■, the only way that works is no ■■■■ at all. Never again.
But I know that there are a ton of minor little habits which would be nice if I don’t have them. But if I tell my self that I will never do them again (like chewing on my fingernails) I will end up with a huge list of things I mustn’t do ever again. I will feel horrible since never again is a pretty long time 
What I found out for my self is that there is an easier method to get rid of them.
Every night i define goals or small, easy “challenges” for the next day. Like “tomorrow I will wake up and drink a glass of water” or “tomorrow I won’t watch twitch”.
Once a week I will set one larger goal. This week was “I will keep my phone in the living room when I’m at home and I will use it for less then 30min daily”.
The important part is, that each night I will look back at the day. I feel satisfied when I reached my goal and I see that it’s not torturing to do it like this and my day was better then if I did it the old way. From the bad things during the day I can set a new goal for the next day.
It’s an easy challenge and reward system which helps me to change my bad habits step by step without torturing myself.