If you have pinholes in your welds its from contamination. Your metal isn't clean or you have no gas coverage (welding outside?). Be sure to grind off any rust, paint, undercoating, etc. before you try welding.
Spend a lot of time prepping. Be sure your parts are held in place well, gaps are a burn through waiting to happen.
Try what I call the "BB Method"... AFTER you have good settings for welding the thickness.
Without a hood but with a good leather welding glove on your free hand, aim the wire at where you want the weld, cup the glove over the nozzle to shield your eyes and squeeze the trigger for about a second - just long enough to get a tack the size of a BB. Move 180 degrees from there and repeat. Now put a tack between each of those and keep moving 180 degrees and keep tacking between tacks until you have tacks about one-inch apart.
At this point you can begin to "connect the dots" again moving 180 from your last bead. Use an air gun or wet rag to keep the metal cool.
It takes practice. Be patient and most importantly, make sure what you are welding is clean of rust, paint, undercoating, etc. All that stuff does is just contaminates your weld.
