As you may or may not know, there are many many ways to introduce colorwork into your knitting. There's Fair Isle or stranded knitting, which I discussed here. There's mosaic knitting, which you can try with this pattern:
There's intarsia, my Lex Luther:
And then there's my dear, dear friend, mighty duplicate stitch.
Duplicate stitch allows you to create one section of colorwork that you would have to knit in intarsia otherwise. No bobbins, no trillion strands of yarn tangling everywhere. It's essentially an embroidery stitch that mimics the look of the knit stitch. Here's how you do it. Start with a graph. You can make your own with graph paper [note: knitter's graph paper is available, but I just use regular graph paper] or use the colorwork chart that comes with your pattern. Cross-stitch and needlepoint charts will work as well, but keep in mind that they do not compensate for the size of the knitted stitch as a chart written specifically for knitting will.
(that's a smiling face, folks). Notice that the design is slightly elongated top to bottom, as compared to the finished result below. That's because regular graph paper is composed of squares, where the knit stitch is more of a rectangle.
Finished result, much shorter vertically than the graphed design.
Here we go. Each block of the graph represents one stitch. Thread some yarn onto a yarn needle. I usually use 12" lengths of yarn. Bring the yarn up at the bottom of the "V" of the stitch you want to cover:
Next, bring the needle through the tops of the V of the stitch ABOVE the one you want to cover:
Bring the yarn through. Don't pull tight. You need very little tension on the stitches. You want the duplicate stitch thread to cover the stitch.
Now bring the needle back into the bottom of the V where you first came up.
Done and done.
It's easy! You can add designs or embellishment after you're finished your garment. It's great for putting initials on kids' sweaters.
Or make up your own motifs - this was for my train-loving son. Please note awesome smoke, which I am very proud of: