1-MCs are not perfect! They make mistakes, have thoughts they shouldn’t and do things that should not be done
2-Don’t make it obvious your MC is making a mistake! MCs are not dumb. Just like you and me, when they make a mistake they think it’s their best option
4-Be consistent with slang and linguistic affectations. Have you ever noticed how a friend of yours says totally all the time? Or like? Or bazinga? It does not matter what it is, what matters is that your linguistic weirdness does not permeate the speech of all of your characters. Different characters will have different affectations. Don’t overdo it!
5-Don’t make your MS gorgeous in a stereotypical way. It’s harder to relate to MCs who look perfect since most of us don’t, at least according to TV standards. We all have a charm the way we are, so rather than promote this idea of the superhuman as the only lovable option, make your MC unique and have them shine the way they are! Support your readers!
7-Don’t have your MCs make the same mistakes over and over again! It becomes annoying and boring.
9-Don’t have your MC be a stereotype! No one is a stereotype! A stereotype is at best the average of what the majority looks like. At worst is the racist interpretation of what you think someone is like, based on ignorance. If you want your MC to be a specific race, sexual orientation, religion, etc… make sure you do your research on yourself or someone else. Talk to friends who share the trait you are interested in delving in to make sure your character is accurate yet unique. If you have no friends and no direct experience about whatever trait you want to talk about, guess what? You probably shouldn’t.
10-Love your MC with all of their faults. To write a great MC you have to come to accept that you are not perfect and that’s okay. Only if you manage to embrace the way you are you can come to describe MCs who are unique, believable and relatable.