if u want to make a perfect aluminum bead, you have to have experience

Practice, practice and practice on AL, will get you the above. experience comes from doing, Practice is doing. every one had to start at some point. yes its a tuff weld compaired to steel, but doable. if you want to weld aluminum jump in and get started at it. get some scrap (cut off's) so you have nothing to fear about screwing it up. clean it up and start Practiceing. in time your beads will be good solid welds and some time after that they will start looking nice too. wory about a good solid hold first, looks second. take your time and dont rush it.
if you have some thing comming up soon that needs aluminum welded its probly best to sub it out. take your time and learn it right.