I have the cheap CRAFTSMAN brand MIG and am very happy with it. Obviously GAS-Mig is better than gasless, but if your MIG is gasless, I would suggest experimenting with scrap metal. Try putting your tip at different distances from the weld. I tend to get nice results at about 1/4 - 1/2" from the weld. This helped more than anything else I tried. Unless I am working with sheet metal, I leave it on high power. I welded a lot of parts for my car that had to be water tight and air tight. My gasless mig did fine. I wish I had a closer shot of some of the welds, but here is my exhaust done with a gasless mig.
Good Luck!
Good Luck!