When making my Palmies, I found a few things that really simplified the process.
Place all of the front stitches on a single double-pointed needle (for the medium size, that's 24 on one needle, 12 on each of the other two). This way you don't needed a marker to show the start/end of the pattern and there are no ladders formed in the pattern section. It seems like it might be awkward to knit this way, but it's not really.
When doing the thumb gusset increases every third row, use a sticky note to keep track of which row you're on. This is very low tech, but the easiest way for me - I can tell visually which of the three rows I'm on and which increase I'm on.
Use thin stitch markers to prevent extra slack in the adjacent stitches (I just thought the looser stitch looked ugly).
Keep track of how many rows you do in the ribbing, then in the mitt body and write both numbers down. It makes the second mitt a lot easier. I use a locking stitch marker on the back of the mitt to note specific rows (30, 40, 50, etc).
The next post will be tips for working the finger openings.