I couldn't agree more with Craig. In fact, here is the post I wrote that explains Craig's point even more...
The technical side of resistance training should be your primary concern right now. There is nothing wrong with lifting weights or performing bodyweight exercises, the key is to ensure that your execution is correct.
Compound-based exercises that involve several muscle groups is the best recourse for younger participants.
-Squats – these can/should be done un-weighted at first with a strong emphasis on correct execution. Have a qualified professional in your area address this issue.
-Lunges – same as above.
-Push-ups – these can be done in either a vertical (against a wall), or horizontal (traditional) manner; it will completely depend on your current strength level and how strong you are through the torso.
-Deadlifts – same as squats and lunges.
-Various pulling exercises.
Again, technical execution is your primary concern.
If you are able to purchase a book, why not instead hire a QUALIFIED professional in your area who can ensure your technical execution of these exercises?
Also, you have to understand that developing a younger athlete is not a simple matter entailing ‘basic’ advice. ANYONE who comes on this message board with advice for you claiming that they have THE answer is wrong… without a complete knowledge of your sporting background, eventual goals, current sporting habits or postural screen, any advice you receive over the internet should be taken as informal guidance. There are right and wrong things that are basic to your age, but even that is misleading since your chronological age does not necessarily reflect other factors such as biological efficiency or emotional maturity. Not to mention motor skill development (which is the primary basis for strength training and kids), flexibility or speed enhancement… You get my point… Any advice here will be basic at best.
Craig Ballantyne is an excellent resource. Some folks would say that I know a bit about youth athletic development as well… You could go to either of our websites for more information.
Good luck!
-Brian
www.DevelopingAthletics.com