Oh boy. Here we go.
First off. Mixing starts with the recording process. You're already talking about "fixing" bad performances.
No offense to your current abilities, but you have quite a lot to learn.
Study, study, study. There are stickies in almost every subforum. Read them.
There are basic recording and mixing "how to" videos all over youtube. Watch, learn and practice.
People on this forum can be very helpful, but don't expect anyone to hold your hand and walk you through it all.
Learn, practice experiment. You gotta put in the work
Good luck.