Yup, even with steel i usually won't end on a corner for that reason and arc blow with stick. Try a bit more wire too, that might help. Also get a stainless wire wheel for cleaning right before you weld, i know that helps when tigging it, might not matter for mig. I haven't done a bunch of al mig, but from what I've done it's definitely the easiest way to do it. Tig isn't bad with the right machine, and I've done some pretty cool stuff with it (the carb on my welder for instance), and stick can work fine too, but mig is really easy in comparison.