Man, it took me a lot of practice before I stopped blowing holes in things. Your beginner booger welds are something to be proud of - your first teetering steps into a new skill. Just make sure you get a decent breath mask - welding fumes don't stink too bad, but inhaling it over any decent period of time will fuck your lungs and sinuses.
Also, an extra tip - when you inevitably invest in some sort of subtractive metal shaping tool for builds down the road, get an air-powered die-grinder. Don't buy a Dremel - they're all speed and no torque, and for anything bigger than baby jobs, especially with metal, speed just makes noise, torque does work. Dremels will just torque out and stop in anything harder than blancmange unless you take it real slow, but a good die grinder will chew through and have plenty left to give you. You can get decent enough ones for the job reasonably cheap, and quality tips can be had reasonably cheap. For jobs the size of the ones you're planning to do, they're a better investment than a grinder, since they can handle both small, fiddly jobs, and bigger grinding jobs, with the right bits.