Make sure your saddle tree fits your horse's withers! This is a very important point! The saddle needs to fit you, but first of all it MUST fit your horse.
If there's a good saddlemaker in your area, you could learn a lot talking with him. Beginners will often buy a saddle with a padded seat. Some folks prefer them, but most riders prefer a plain seat. I second the idea of buying the best you can afford and staying away from the synthetic trees and tack. Western Horseman magazine, and other good horse magazines, have articles on saddle fitting from time to time. Maybe your library could come up with some back issues. If nothing else, talk with a horse trainer, breeder or 4H horsemanship leader. Take their advice over that of the salesman at the feed/tack store. Again, your best source of advice would be a good saddlemaker.
I had a custom saddle made by an excellent local saddlemaker. He spent so much time fitting that saddle to me and to my horse. He had me come over a couple of times to sit on the saddle during various stages and see if it was fitting well. I am tall and have long legs (I buy 38" jeans). One thing he taught me was that I needed a slightly larger seat so that I could sit back just a bit. That made all the difference in the world when it came to leg comfort. He taught me it's not just the length of the stirrup leathers. Other parts of the saddle come into play when you have long legs.
Good luck to you! I hope you are able to put together some good tack that will fit your horse and you.
