When to put a Comma

I actually do have troubles with Commas. I don't really know when it is necessary to add a comma. For the most part I don't have trouble with the comma splices, I just like to add to many commas, because I think it might need one, then when I get my paper back I have all these marks that mean take away the commas. HERE is a good place that gives 3 good myths about when to place a comma.