As an amateur hack, I've found one of the best things I can do, whatever I'm doing (O/A, stick, flux core), is to pull some scrap from my pile, throw it on my bench, and tweak my setup.
A good quality MIG setup makes things almost foolproof, with just a little bit of knowledge and practice. My Vo-Tech instructor always said he could certify students on it in a matter of a few hours. I wound up selling mine. I don't do much fabricating; keeping it setup and working for my infrequent repair jobs wasn't worth the trouble.