Q: How do I start?
A: Start by reading the stickies and read as many posts as you can. If you read all the stickies, and then try it out, you will get the hang of it very quickly.
First off, you'll get better results doing pep than you will doing cardboard. It's a little more expensive than cardboard, except with much better results. You will probably not do any molding work, mostly because it is HELLA expensive, and hard to do.
Q: How long does it take to make armor?
A: It depends on what model you use (Halo 2, Halo 3, or High Def), how much time you put into assembling it (generally, go fast, get sloppy; take your time, get good results), how often you plan on working on the pieces, how many times you mess up and have to restart, and what pieces you plan on making (Helmet only, or full suit). Summed up, it can take a very long time if you take your time and make the HD models, or still a while if you rush with low detail models.
Q: Is it very hard to make good armor?
A: Generally, yes. If you want the best pieces you can get, you will have to make the HD models (which are pretty hard), make sure to take your time and go for perfection, then fiberglass at least 2 times, and bondo and detail, which is the hardest part (remember, the more detail included in the pep model, the less detail you need to add while detailing, thus it is easier to make the HD models.)
Q: How much does everything cost?
A: A full pep suit can cost several hundred dollars. If you happen to have card stock, hot glue, resin, fiberglass, bondo, or paint laying around, you can save some money (I had almost all of those at my place

). Card stock and hot glue aren't very expensive, but the resin, fiberglass and bondo are where the money goes. Paint also can add up. You need to have some cash, supplies, or parents that are willing to pay to make a pep suit. IT IS NOT EVEN CLOSE TO FREE.
Q: Can I make it if I'm 15?
A: Age doesn't matter. All you need is patients, a little skill, and some money to do it. I'm 15 years old as well, but I don't let anyone tell me I can't do something because I'm young (Except drive, or something else that is a law

). There are some 12 year olds that can do some good stuff.
Now, read up on the stickies VERY well. Read them over and over when you have questions, and if you can't find the answer, use the search button. If those still yield no results, then you might be able to post your question in a topic. It is frowned upon when questions that are answered in the stickies are asked.