hi all may sound a bit silly, but it's been a while since i stick welded but do you push or pull or can you do both to get different levels of penertration?
As Sparkey says Ben, you pull - electrode 0-10-20-30 degrees off the vertical, depending on the electrode (some need to be perpendicular to the work for full shield coverage). BUT... if you're on the vertical, you are most likely to be pointing a little uphill, whether you're going up or down. If you're welding horizontal-vertical, you'll be pointing up a little, and back the way you've come (so pulling).
There are books which will tell you more. Look here for clues.