You've got time to do three things-get yourself in shape for hiking, buy appropriate gear and clothes and learn what to do. For getting in shape, you can do walks around your neighborhood wearing your boots or shoes you plan on using and a pack loaded to the approximate weight you will be carrying. Water jugs will work for the weight. Start slow with short walks and work up to longer walks.

Read-The Complete Walker by Colin Fletcher, often found at your local library or available from Amazon and other booksellers. This is the "bible" of backpacking. There are other good books, but this one has all the basics in it. Fletcher died a few years ago, but the book carries on with a co-author.

As other members have said, don't buy gear at random, buy your pack last (you buy a pack to hold your gear, not to fill up with gear you bought and consider each part of your gear selection as part of a system, like building a house. You don't buy construction materials just because they are on sale, you buy what you need. Same idea.

Altitude-this could be a problem. They only real way to adjust to altitude is to be there. I know this from living at 12K for a year or so. Not everyone acclimatizes the same way. Getting as fit as you can will help.