Lots of stitches.

I've just made a blanket for a friend who is having a baby.

  Here is the back if it, which I think looks pretty cool, and below is the right side.

I loved it, because it uses two balls of wool at once, so the pattern is 2 rows plain in colour A, then 1 row plain, 1 row purl in colour B. To get the stripes, you start with just 3 stitches cast on, then at the beginning and end of every other row, increase 1 stich by knitting into the front and the back of the stitch. 
Once one side is the required length. Instead of increasing at the beginning of every other row decrease. (slip stitch, knit one, pass slip stitch over). Then increase at the other end, so as to keep the same number of stiches. When one side is the correct length, start to decrease both ends on every other row, casting off once you are down to 3 stiches. I finished off by crocheting all the way round, picking up stitches, one single crochet, one double crochet, repeat till finished.