How to trust?

I have issues with trusting people (like we all do). Everytime I try to trust someone (as I’m trying to work on it and not project onto someone new) they give me a reason not to trust them and it hurts. I obviously don’t stay…but I’m worried that having a lot of these experiences is making me think that betrayal is normal. When someone truly genuine comes along I really don’t want to mess it up by not trusting. But atm not trusting seems to be the only thing that ensures I don’t get hurt. It feels like a vicious circle- I open up a tiny bit and get stung, which then makes me shut down even more. What should I do - I genuinely want this to stop.