Once you get comfortable with the controls and movements and everything, one thing I would recommend is watching Youtube videos of pros playing your favorite character. You can learn a lot about your characters potential that way.
For Glory will make you a stronger (and angrier) player if you're willing to not give up playing online matches. I got a lot better playing as Marth online after battling various people. Once I felt comfortable with him I started to learn and main other characters as well. I think if you can nail shielding, dodging, and grabbing things will become a whole lot easier.