First of all, there are several kinds of strickfingerhuts and the kind shown here is NOT the preferred kind to buy. Instead go for a metal one that looks like THIS as it fits your finger better, won't break, and holds the two yarns farther apart which is the whole purpose of this handy gadget. If you google "knitting thimble" you'll find a wide variety - there is even a type that fits over your fingertip like a sewing thimble.
The biggest advantage of using the plastic type shown here is that it can hold three or four yarns. In fact it may even be the best method of knitting 3 colors per row without excessive yarn twisting. Anyway, they're all around $3 so get a few and play with them.
Strickfingerhuts are mainly used by Continental knitters although I occasionally hear of a right-hand knitter who has figured out a way to use one. It normally goes on the left index finger and I like placing it as far down toward my middle knuckle as possible. That way I don't have to lift my index finger so high while knitting.
To use the plastic type, you open it up and insert the strands of yarn and close it up again. With the plastic type I put the two yarns as far away from each other as possible.
To knit the lower yarn you simply go over or under it and grab it and pull it through the knit stitch on the needle.
To knit the higher yarn try doing it similarly to yesterday's post on two colors in the left hand - grab the higher yarn by going over it and pulling through. You can use the rest of your fingers to hold/tension the yarns however you like. Many Continental knitters say that this handy gadget has greatly increased their 2-color knitting speed.
Tomorrow I'll talk about two-handed two-color knitting and this weekend I'll discuss some methods of knitting 3 color rows.
Here are my latest Roy G Biv socks knit in worsted weight yarn from the stash. I wish I'd been able to find a brighter yellow in the stash.