Hello Beginner,
You've gotten some good and bad advice here. The suggestion to visit SOTW is excellent. You can learn a lot there. Don't, however, assume that because someone belongs to SOTW that they are necessarily honest or well informed, although there are many very good members.
Yamaha makes a great student horn and they idea that a YAS 23 isn't a good choice is nonsense. They are very well respected student horns.
If there is a large music store near you, go and try as many horns as they will let you. If not, many online dealers offer trials which will cost you shipping only if you don't like the horn.
There are horn snobs that will dismiss Taiwanese horns as all being junk, but Cannonball, Antigua Winds and Kessler horns all have decent reps. Check out http://www.kesslermusic.com/ Dave Kessler has a very good reputation. Just call him; don't email. He is not good on answering emails.
If you want to consider a vintage horn, it is very hard to beat a Buescher True Tone or 140 Aristocrat for value. Either horn can be bought in excellent playing and cosmetic condition for under $1000.00 Either deal with an establish seller with a return policy, or start educating yourself and be careful. Nice silverplate True Tones go through ebay regularly for 5-700 dollars. 50's vintage 140 model lacquer Aristocrats will run about the same as long as they don't have the "Big B" engraving. Don't even consider buying on ebay without very savvy and experienced help.
The main thing is, play as many horns and mouthpieces as you can and buy the one that makes you want to play. Then find a good teacher.
Good luck.