How to make good choices using Buddhist principles?

Do you regret some of your past actions?

Regret is rooted in self-blame.
Regret is an emotion that arises when you don’t understand yourself.
It’s foolish to blame yourself and feel regret for what has already happened.
Instead, view it with a light heart and accept it was simply a mistake. 
Vow that you won’t make that same mistake again and then move on.