Clean metal before welding. Use a stainless steel brush to remove surface debris and use a degreaser to remove surface grease and oils.
Ensure tight fit-up of the metal surfaces that you will be welding. Less than tight fit-up results in holes that beg for burn-through and leave a gap that cannot absorb heat.
Place a backing bar, generally made of aluminum or copper, behind the surface to be welded. A backing bar will absorb heat, thus lessening the warping effect that heat can have on metal.
Create small, uniformly-sized welds at equal distances from one another. This process, called skip welding, avoids excessive heat-treated zones and helps to balance the welding heat over the complete area of the welded surface. After traveling around the area to be welded once, create a new set of welds at equal distances from the first set. Continue this procedure until your welded surface has the integrity that you desire.
Direct the arc at the middle of the weld puddle. This allows the weld puddle to shield the metal underneath from the heat of the arc. Avoid whipping or weaving the torch; instead, travel in as straight a line as possible. Use the fastest travel speed possible that still allows for a uniform weld bead.
Avoid over-welding. For instance, if welding a 1/16 inch plate to a 1/8 inch plate, your weld need only be 1/16 inch long. Over-welding not only leads to distortion, but also to wasted materials and time.