I am looking into getting a black lab. I already have a 3 year old cat and I am wondering what I can do to help them get along?? What are your suggestions?

Your best bet would be to try and find a puppy (assuming you are looking for a puppy) whose been raised with cats.  This will give you a head start, as hopefully the pup will have learnt not to chase the family cat - then you will have to teach your puppy not to chase *your* cat, which should be a lot simpler than taking a puppy who hasn't learnt anything about cats........