I have found these items to help me when I weld flat panels together.
Keep your air gun close, and use it to cool each weld as soon as you weld it.
Move around, stay as far away from the last weld as possible.
Go slow, If the metal is too hot to touch, it's too hot to weld.

Wayne
1938 1-Ton Farm Truck
Stovebolt Gallery Forums
1989 Silverado
1996 Mustang GT convertible
When I die, I hope she doesn't sell everything for what I told her I paid for it!