I would try practicing on some thicker material, perhaps 18gauge, and practice a fillet weld on a T-joint.
Hold the welder so the nozzle is at a 45* angle, and then tilt it slightly so you are "pushing" the wire. You keep the weld puddle 50% on each piece. If you're right handed, I would weld from right to left.
This all happens very quickly, but when you start welding;
-Start your puddle, try for a 1/4" weld.
-Try stitching/whip. Once you have started your puddle, move forward, then back into the puddle. IE. 1/4" ahead, 1/8" back, 1/4" ahead, 1/8" back. etc.. Keep time like a metronome. Say, 60bpm = 60 cycles of moving ahead and moving back. The shorter the whip, the less chance of undercut and inconsistency.
-Move at the speed that keeps the weld 1/4".
-Practice more, you can stack your welds after you've welded one pass. You don't weld directly over the other weld, rather on the edge of the weld.
-After you've welded you can learn a lot from looking at it. The discoloration shows an even weld travel speed, etc. The brown smoke to one side of the weld shows I wasn't exactly at a 45* angle to both parts, or the smoke would be even on both sides of the weld. You can see the motion I moved, as the weld has textured >>>>> as I whipped it.
And practice practice practice.