I came across this the other day. It's a generic mitten pattern you can do with any size needle, any yarn. It's based on your gauge and your own measurements. I'm currently knitting a pair based on this and it's going quite well. The only thing I would caution is to add about four extra stitches if you're doing the Fair Isle type that she has pictured. The Fair Isle pulls the work in a little and will make the mittens snug. So far, I'm finding they're a good fit. One thing I never thought of was my odd size hands. I have small wrists and wide hands. I had to increase a few stitches after the cuff to accommodate this, but it's working well. This is the first mitten pattern I've done that actually fits.
http://www.hjsstudio.com/mittens.html
If you're knitting mittens for someone else, have them trace around their hands on a piece of paper. Just in case they're not around or are at work or school. Little kids don't like it when you constantly chase them around the room with a measuring tape.