I always read topics like these and I still fail to do them, (I know how I just miss doing them before writing the story and sometimes long after)... Thanks for reminding me of this.
everyone has something they wish they could change about themselves.
I think that's a weak point of a lot of my characters, a lot of them are content with themselves. I'll try to work on this.
Give your character a secret.
This one is very good advice... But I can't think of a secret that I don't want to show to the reader... But if done right, this secret can influence everything the character does and makes the readers engaged with thinking the reason.
Everyone has flaws. If you give your characters one I am willing to bet they will be more relatable.
The secret can be big, or it can be something small- like they bite their hangnails or pick their nose, but they want to project themselves as perfect so it's a big secret to them, they'd die if anyone found out ;)