Overhead/out of position is fun...I turn the speed of the wire down a bit, and lead and loop back in very small circles...you really need to do it, and get the feel of it for a while before getting in there and burning the real deal...
I practice on similar material in a simialr position for a bit before I do the real thing...
Overhead welding is a pain no matter what type of welding process. Even though we practiced this in welding class, I never really got the hang of it, although I was better using OA or TIG because you have more control. The idea is to move fast with a minimum current. You may need to do multiple passes on thicker material. The one thing I remember is don't do it in a T shirt.
Run the bead sideways. If you run tward or away it is harder to see the puddle. There is also a fine line where you can adjust the heat of the arc in the middle of a run by getting the arc closer, or further from the material. It is defiatly something you don't get easy. Practice alot on scrap.
Clamp a piece of scrap to something yo hold it ovehead. Find a comfortable position, and make a few passes. once you get the feal for it you will know what the weld should be doing when your in a bad position. Not only watch the weld, but listn too.
Just practice, practice, practice and wear your welding leathers - you're in for a shower. I have had a hard time adjusting to welding overhead with my new MIG machine, still tempted every time to get out the old stick machine.
I've yet to make a pretty weld but slightly higher heat to make up for the more acute electrode angle and slower wire seems to work the best for me - and a couple passes.