If you're buying your first hula hoop, a couple of tips that I can offer you are to notice the size, the weight, and the material that your hoop is made out of. I have a couple of examples here of different sizes. I would suggest for everyone buying their very first hoop, to go with one that is about the height from the floor to your belly button. It can be a little higher or a little bit lower, depending on what is most comfortable for you. That is what I find to be the most ideal diameter. It's usually about 39 inches, give or take.
As far as the material, you want to look for something that is lightweight but still has a nice weight to it, and is usually one inch or three-quarter inches in width. The hoop I have here is three-quarter inches. One inch is also a great size for your very first hoop.
Then the next thing that you want to think about is the taping design, do you want to have tape on it. It's not necessary to have tape. It's really helpful to have some kind of cloth tape to help the hoop have a little bit of texture and grip so that it will stick to your body and your clothing whenever you're trying to hoop with it. It's really, really difficult to hoop with a hoop like this one that is completely smooth, even though it might be very pretty, it's difficult to keep it on your clothing because it's so slick. So go with on that has a grippy tape, it's about 39 inches give or take, the height of your bellybutton, and it's no more than two pounds. I would not recommend using any weighted hoops, or hoops that are more than two pounds, not necessary.
Hooping is an aerobic activity and not weight training. So anything more than two pounds is probably going to cause some discomfort and bruising. And those are some things to consider when buying your first hula hoop.