Well i have an omega rear door to practice my welds on ,
going to angle grind some squares out of door an see if i can weld
them back in seamlessly
If you are learning to weld, in any shape or form, use clean unpainted metal with a good clean earth point, otherwise it will frustrate the hell out of you when you get bad results.
It's all about controlling the pooling, regardless of what weld method you are using. Arc is better suited to angle iron/box section (cleaned off in area of weld). Only thing to control with Arc is the heat setting so relatively straight-forward, but when you are new to it the rod is long and awkward, your hand will shake and you will have the desire to waggle the stick all over the place. Get the heat right for the material thickness , a steady hand, a good clean clamping point, a crisp constant crackle and you will be sorted.
After twenty odd years of welding on a daily basis (doing a different job now), if it doesn't sound right, it ain't welding right.
Dirty metal can make a good welder look poor, but then again a good welder would know this.
Good luck, you'll get there eventually.