One of my favorite books, Sara B. Stein's A Family Dollhouse, gives directions for a knitted blanket that anybody can make. I'm a beginning knitter, with only three plain scarves to my credit, and if I can do it then definitely anybody can.
You don't have to count or measure or guess at anything. You don't even have to purl! According to Stein, this was how soldiers' blankets were knitted, and even children can do it.
Cast on one stitch. Knit every row; increase one stitch at the beginning of each row. When one side of the triangle is long enough to suit you, then you start decreasing one stitch at the beginning of each row until you are back down to one. Then bind it off by pulling the yarn end through it.And that's it! Weave in the two ends, and you have a nice blanket for your doll. Here's a picture of how this looks on my needles. I think variegated yarns are helpful for beginners; since each of the stitches is a slightly different color, it's easier to see what you're doing. Like all my other projects, this one keeps me busy while awaiting my Yren.
I'm using this method to increase: Knit in the front loop of the first stitch (but don't remove it from the left needle); knit in the back loop of it, then remove both new stitches from the needle at the same time. This way of increasing makes a nice edge for the blanket.