Step 1: Things you will need
-fabric, however much you want depending on the size of your blanket. I like to use polar fleece types of fabrics, but I have also used flannel for thinner blankets.
-Blanket binding, enough to go around the entire edge of the blanket. You should be able to find blanket binding at fabric stores, but if you can't find any, you can use satin ribbon, at least 2 inches wide. Iron the ribbon so it has a crease down the center and it becomes blanket binding!
-sewing machine (I guess you could do it without a machine, but it would take ages)
-pins, lots and lots of pins
Step 2: Prepare your fabric
Sometimes when you buy fabric, it can be cut at an angle or it gets stretched out and will not be in a perfect parallelogram. If that's what you're going for, then go ahead to the next step, but if you want a square or rectangular blanket, take the time to make sure all the sides line up evenly. Do this after you wash (and iron) your fabric. Give the cut off pieces of fabric to your cat.