First, time. You are very vulnerable for at least a year, perhaps longer especially if the relationship was long or your only serious relationship. I got together with DH after 10 months and although he is fine, I think I was lucky - there were a few things early on that if he had been abusive, I wouldn't have been able to walk away from. I just wasn't strong enough, even though I had thought I would be.
Second, you need to be fulfilled by your own life. If there's a gap in your life that you're waiting for a man to fill, it's much easier for an abusive man to fill it. They go around oozing into those gaps, they thrive in them. Close the gap. Think of yourself as more of a jigsaw piece, with "inny" and "outy" bits - you want them to enhance your life and for you to enhance theirs. You complement each other, you fit, but you don't need him to basically become the most important part of you.
So - do things that make you feel proud and capable. Buy a tool kit, start a project, look into old hobbies or new ones, make a five-year-plan, make general plans for the future and start taking steps towards them. Make your home really feel like yours, especially if it was a shared home with your ex. Paint walls, hang pictures, buy nice bedding. Basically, take some time to figure out who you are and what you like. This fits into the relationship stuff, because it's a red flag to look out for if a new man criticises or disapproves of anything that you do. Immediate dismissal! No second chances! (Maybe ONE, to make sure it wasn't a misunderstanding.) Green flags, on the other hand, are that he is excited and enthused about things that you do, supportive of your plans, encourages you to go for that scary promotion/course/goal. That excitement/enthusiasm is important - if he is just following along approving of and agreeing with everything you say, that might seem better than disapproval, but it's not the sign of a healthy relationship either, it's more mirroring. He should have his own ideas but be respectful and interested in yours too. And of course if your ideas are too different, then you might not be compatible anyway. If he wants to spend every weekend up a mountain or in a wood or down a cave and you'd rather spend weekends curled up at home in front of the TV then you're not going to make each other happy long term. That's another thing you have to get your head around - not every good guy will be the right guy for you, and that's okay. Don't settle for the first person you find who is nice, they have to be a good match for you too.
Third - boundaries. If you've been in bad relationships, your boundaries are probably shot. So do some practising. Set some really small, definitely non-sexual boundaries that seem almost insignificant. A person who respects small, insignificant-seeming boundaries is not going to cross big, important ones. Whereas a person who considers boundaries to be some kind of challenge that they like to slime all over will ridicule, push, wheedle, and somehow get past your boundaries, usually in such a way that you don't realise until after the fact "Oh bum, I wasn't going to let him do that." This is a red flag!! A giant one! When he wheedles his way into seeing you on Tuesday when you said you didn't want to date on weeknights, or making an excuse to look at your phone when you stated it was private, he's going to wheedle his way around everything that doesn't suit him. It's abusive behaviour. People who don't respect boundaries aren't interested in you as a person, they are interested in how far they can push you. It's a power game. Set some small ones as a test and see how they are reacted to.
I should add that the boundaries thing is a huge part of the "bad boy" attraction. So this might be something that you really need to do some serious work on. People (men) who disregard boundaries are really, really practised in how they do this. They have a way of making us feel that it was our own decision, which is sexy, seductive. Addictive. To say "I don't want him to do this" and for him to get you so worked up that you beg him to do it is incredibly powerful and a draw. It can feel like it would be boring or perhaps even scary to be the one in control. It feels really awkward at first, granted. It can even feel a bit of a let down. "What, you're just going to accept it, just like that? You're not even going to fight me for it? Tease me a bit? Don't you want me??" You have to reframe this and think "Wow, this person thinks a lot of me. They don't want to risk pushing me away or pushing me into something I'm not ready for. They are happy for me to be in control."
Don't worry that you're missing out on something by doing this. A person who respects your boundaries generally in life can still be exciting in the bedroom - even more so, actually, because you feel so much safer with them knowing that they would stop the moment they noticed you not feeling 100% into whatever is happening. With a person who disregards boundaries, those first kisses etc feel exciting but after a while sex becomes an ordeal or a chore, because it's all about him. With a person who respects boundaries sex tends to stay good because you're pushing new ground together, communicating, in touch, he is more aware of you.
You can look for those red flag lists, the relationship with his mother, the way he treats waitresses or talks about other women, etc, but fundamentally these three things are what you need for a healthy relationship. Time, independence, boundaries.