What kind of hoop should I get?
Bigger = Easier Heavier (up to 2.5 lbs) = Easier
Don't: buy a hoop from Wal-mart! Those are kids' hoops. If you think you can't hoop, you have probably been trying with kids' hoops, which is akin to going to the children's shoe department and expecting the shoes there to work for you, and then blaming yourself for your lack of ability.
Don't: pay $45 for a "5 lb weighted hoop". This is a gimmick. There is a myth that the heavier your hoop is, the more of a workout it is. That's silly!!! You get the workout from the cardio, not from pushing a 5lb hunk of lead around your belly. Be nice to your kidneys! These are hoops are dangerously heavy and you will not enjoy hooping with them for more than five minutes.
DO: get a comfortably large beginner hoop to start out with. Hoops come in sizes up to 48 or 50 inches across! The so-called 'rule of thumb' is to measure from your belly button and add 3 inches if you are starting out. Add another 2-3 inches if you consider yourself a rounder person. Still... the size you need varies so much based on your ability alone! Most of the hoops that my beginners start out with are between 43-47 inches. Don't be afraid to start big. You want it to be easy to keep up (after you give yourself 10 minutes of trying it out), because the next thing you will be working on is turning and walking with the hoop, and this is so hard at first!