^^^That was a little OT so back to the topic at hand..
OK... back to the subject at hand. Since you are new to horses and are buying your first tack, I suggest you buy quality. It will cost more up front but with care it can last a lifetime. I would recommend you taking the tack that you have with you while shopping. It will make sizing a WHOLE lot easier and give you a solid reference for things that you like and don't like about the tack you have and the tack you want.
I'll add some pictures of what I would buy and why... Hope it helps.
Headstall ~ I like browbands. And I like ties on my headstalls instead of chicago screws. ( I check the ties but not the screws...Don't know why I'm like that but I realize that that, is just me. ) http://horsesaddleshop.amazonwebstor...source=froogle
Reins ~ I like looped reins. I fiddle around and end up dropping split reins. I don't show, and I mainly trail ride, also my horses are well schooled in neck reining. These factors along with the possibility of me having a soda, other canned beverage or cigarette in my free hand also influence my decision on looped reins.
Some of the reins I like. http://www.thetackstop.com/cottonropingreins.htm
<-- Flat cotton roping reins. I love the feel of these. The more you use them the softer they get. I also like reins with snaps at the end. Downsides of these are that they get dirty fast. ( I buy black for good reins/ white for night time things) http://www.enasco.com/product/C27587N
<-- These too are cotton reins, they are split. ( I tie them if need be) Sometimes the popper on the end is handy for a less than willing horse.
I have also used barrel reins (they're a tad shorter) but I like them, I have also used nylon looped reins and not had problems either. I just prefer the feel of cotton.
Hope I helped. These are just what I'd look for. Happy Shopping!!! Have fun and remember if you're not showing, you can buy whatever your heart desires and whatever you like!!! No rules for us happy hackers!!!