I don't think you have to be perfect, and I totally understand how hard this is for you! You are a first-time "mom" and your kid didn't come in a tiny helpless bundle, she came with 5 years of personality and abuse and scars! So just keep learning, that's all you can do.

I try this, it is effective, I try it a bunch of other times. I try this, it isn't effective, I put it back in the tool bag and might pull it out again later.

Kids respond better to praise than punishment, so I love the tip above to catch mine being good and praise her every chance I get. She's very defiant so her punishments really have to hit where it hurts (like no tv time, no dessert, bed time half hour earlier than usual) because trying to enforce any boundary is always a power struggle. Another reason why I have to pick my battles, I can't get into a power struggle every time I need her to do something, it's exhausting.

I think you're doing a great thing and a hard hard job!