You'll learn how to approach things.
I'm a dab hand with the no more gaps now
I tend to do painting (which is what I"m supposed to be doing now), DF does all the cosmetic structure stuff (he's got every tool known). Read instructions, ask at Bunnings, google. I also looked at pictures of posher houses and if I saw something I liked I saved the picture to give me ideas. Just getting started with painting can cost a small fortune though.
Brushes (get the best you can afford and look after them)
no more gaps