It's probably not to hard to repair the relationship with the person who you scared off. Just go back to them and be honest. If they don't like it or they hold it against you that's not someone you want to be friends with.

Lay it out bro. Tell them, I want to have a friend, someone who's got my back so I can have theirs. I'm super hyped about it and I should be because it would be dope. I know I'm not for everyone but I'm a trustworthy dude and when I say I watch out for my friends I mean it.

To avoid getting taken advantage of look for some sort of reciprocal sentiment. But also, trust is not about making sure it's safe to trust. It's a leap of faith. Knowing someday that your trust will be broken but also knowing you're strong enough for that to happen. Then just build your friendship strong enough to survive it.