Best advice I can think of is to spend a couple of hours at http://www.weldingtipsandtricks.com reading and watching the fantastic videos.
I'll bet you discover your mistakes right away. FYI, the Miller MIG and TIG calculators are usually very close. They're dead on for a beginner for sure. They're my "go to" resource when I haven't welded a metal or specific thickness or joint type before.
My thoughts are the same as Marks since splatter is a sure sign of contamination.
Steve
Miller 212
Everlast 250EX
Everlast PowerPlasma 60
Victor O/A
Current Project: 21' Jet Sled Rat Boat.