My vote would be for a MIG or TIG machine, no flux. All flux machines I have ever seen in a professional environment are abandoned and left to die. Where the MIG's and TIG's are still being used and often.
Next best thing? Read the manual, then find a pile of scrap steel in various thicknesses. CLEAN that steel until shiny before you weld. Use a grinder, sanding disc, etc. Get rid of all that manufacturing scale. Go have fun. If you're welding a thin piece to a thick piece, set your welder specs to the thin piece. When you feel a little more comfortable, tackle that actual project. If you haven't welded for a while, break out the scrap and do it all over again before you touch that project part again.
