What is the best way to tie in yarn ends of a crocheted afgan?

Why don't you look up crochet edgings and pick one out that would look nice with your afghan. When you go around the afghan it would cover the knots and if you tried to weave them into the afghan it would be seen and make it lumpy. In regard to washing it if you still have the wrappers from the yarn there should be something on them that would tell you how to take care of it. If you don't have the wrapper give us an idea of what the brand name was and the type.