A couple more recommendations for a newbie:
1. I would avoid mares ...
2. A horses temperament is the #1 thing you need to evaluate next to overall health. ...
3. I would avoid thoroughbreds or arabians,...
I have to laugh, in a good way. The above is excellent advice. I had and used an arabian mare. She was a very very very high strung horse, she really liked to move. I put a tone of work into her, she made a great pack horse for me. However, very few people could ride her and enjoy the ride. I'll never forget the look on my partners face the first time I packed in with him. We were short 1 animal so we had to cut back on gear (I can be really bad at that). I had a pair of pants hanging from the front of the saddle, leg bottoms sewed closed. The pants were full of grain. I had saddle pack bags hanging around her backside, full and stacked almost to my shoulder level. I looked like the Beverly Hill Billies loaded up to move to Beverly Hills. My partner was a horse shoe-er, so he knew horses well. He looked at me and my horse and thought it would be a "horse wreck". I stepped up on her with significant difficulty, and rode out 20 miles, camped for the night, and finished the last 10 the next day, camped for a full week, and rode her back to the trailhead, without a single hick-up.
The only reason I was able to do that, was because I had worked with that horse at least 5 days a week. I had thousands of miles on her, some days covering 50 miles in a day (believe me, she could do that in a few hours) and the horse learned to trust me, as she had numerous frightening experiences with me on her back, ASKING her to tolerate the situation (not telling her), and a couple times, when she got caught up in wire, fencing, or bailing string, when necessary, I literally crawled under her to free her. I do not advise crawling under a horse when they are frightened, but I had done this hundreds if not thousands of times, while she was calm.
But going back to PredatorSlayer's post, he is correct, stay away from arabians unless you have tons of experience with a variety of horses.