So...I looked for a simple pattern for mitts. I found one. I read it. I realized that I still don't fully understand how to read patterns. I gave up trying to understand it and cast 36 stitches onto my double-pointed needles and started going.
I used an enlarged version of the buttonhole technique found on this website to make thumbholes. I continued with the top of the mitt, and closed it off. I went back to the thumbhole, stuck my needles through the stitches around the hole to make new stitches with which to work, and started knitting. A few rows later, I realize that I needed to purl instead, so had to undo everything.
Finishing the green glove, I realized that I didn't have enough for a second glove, so I had to use red yarn. Stupid me didn't count my rows when I knit the first one, so I just sort of eye-balled the size of the red mitt while I was knitting it. That's why the red one turned out visibly bigger than the green one.
Oh well. Lesson learned.
Anyone have any tips for me?