Before I start I want to say again that ANY way you hold the yarns is a good method if you aren't twisting the two yarns. Some new color knitters use the pick up and drop method which involves knitting and holding only one color at a time and letting the other color hang. Unfortunately the pick up and drop method is really really slow so do try out one of these methods this week to see if it will click with you.
I think the shape of knitter's hands really dictates which method will feel the best. I'm going to show four different methods this week - five if I can find my strickfingerhut - but there are even more methods than that.
TWO COLORS IN YOUR RIGHT HAND
I've read that most knitters in the U.S. knit using the English/American/throwing method. When I first began knitting with two colors, I used this method of holding both colors in my right hand.
Here's how you start. One color over the index finger in the right hand and one color over the middle finger.
To knit with the red yarn, simply flick your index finger UP and grab the yarn and wrap around the right hand needle.
To knit with the black yarn make sure your index finger returns to being between the red yarn above and the black yarn below as is shown in the first photo here. Then move your index finger DOWN and UNDER the black yarn.
Pull the black yarn around the right hand needle. It is hard to see in this photo but the red yarn is ABOVE the black yarn.
Voila! You've now knit with both the red and the black yarns. Your right index finger does the bulk of the work. Return to the position shown in the first photo after each color change.
With this particular method the black yarn is held ABOVE the red yarn on the back of the work. This means that the red yarn will be dominant; i.e., the red stitches will be a bit larger and more noticeable in your design. Generally I use the dominant color for the design or foreground color and the other color for the background.