There is only one way to get better at welding. Just do it! You have to burn lots and lots of rod. Working in a fab shop is a very good way. Burning rod, wire, filler 8-hours a day, is a good start, but you always need to challenge yourself! Get good with plate in all positions, then work on open root plate in all positions. Then test your welds with some destructive testing. Once you're satisfied with the results, then move onto pipe, start with 2-G, then move onto 6-G, then 5-G. Once your satisfied with the results, do some destructive testing on your pipe welds.
It's a very long road to being a good weldor.