Your keywords should have, at least, 500 searches per day. You'll get a small fraction of those searches as visitors and even less as purchasers. Remember... traffic is only a piece of the puzzle. You must have conversion (people who are buying your product or offering) When you start getting the traffic, remember to maximize your conversion by testing, testing, testing.
I use fb ads always... and fb trafiic is good.. i got many sale today.. if anyone want to join with me can PM me...