It all depends on your goals. Are you looking to bulk up or just get back into shape. I think a good general rule is 3 to 4 sets of each excercise with 6 to 10 reps per set.
Since you are just starting out, I would stay away from too heavy and make sure your form is correct while performing sets. It's easier to keep good form with less weight. As you develope your muscles add weight. Start with a simple 3 sets of 8. Once you are doing sets of 10, add weight rinse and repeat.