I love to knit socks. The ribbing and ankle of my socks fit my wrist and hand fine so I used that number for my mittens.
Using size 1 1/2 needles because I used color work and sometimes I tend to get a little tight with it. Cast On 64. Work wrist ribbing for at least 1 1/2 inches. Using the Philosopher Wool method of color knitting I jumped into assorted graphs and patterns readily available or made up. When the mitten was at the right place for my thumb to be I used waste yarn and knitted 16 stitches at the front end of the row. One needles worth. drop the waste yarn leaving enough ends on it to tie them together so they don't get away while i knit the rest of the mitten. REKNIT that same needle now it will have waste yarn on it, not mitten yarn. Knit all the way around. All four needles. the waste yarn needle now has sock yarn on it. continue til mitten is long enough to begin decreases. dec as for socks. end off.