Knitting with more than one color - how do I start?

I’m trying to knit a child’s sweater. This is the first time I’ve ever tried a sweater, and the pattern is very simple, the only “complex” stitch is M1 so it should be fine. The pattern is of Spiderman’s face, pretty basic. I’ve seen videos on how to twist the yarn so you don’t have a hole. My main problem is, how do I start the pattern? Do I tie the new color onto the back of the main color? The wool I’m using us just plain medium worsted, bulk weigh #4. It seems that every video I see showing how to do a pattern, they start right in the middle of the pattern! :thinking: Any help would be appreciated!

http://www.sweaterscapes.com/intars.htm

Here is an site that talks about intarsia. They say it’s ok to tie a knot. I’ve always twisted the yarn in for a few stitches before the start of the new color, but tying a knot and weaving in the ends is ok, too.