General tips:
Keep a training journal, and keep close track of what you lift. Set personal records for various reps per weight for the variety of exercises you do, then try to break your personal records. This gives you motivation to keep going back in the gym to try to improve. Plus it's good to gauge your progress based on what you can do, rather than what you weigh. When I was in high school I wanted to gain muscle mass, but I focused more on the eating than the lifting, and while I did gain weight it was probably mostly fat. I would give the same advice to someone trying to lose weight: pay attention to what you can do physically as opposed to how much you weigh. That way you're dealing with more finite, therefore acheiveable, goals. And if you focus on making yourself stronger, you're good, because to get big muscles you've got to be lifting heavy weights, basically. I keep a training journal with all my records at the back, and at the front I write down what I do each day, then when I break a record I go to the back and fill it in. I'm kind of anal though, some people would probably say to go more by feel.
Do squats (quads), deadlift (hams), bench (pecs), military press (delts), pull-ups (lats) as your primary exercises that you do each time you work out that particular body group. Then add secondary exercises. On the day I do back I always do chins first, then bicep curls after (although some people say do biceps first if you want to target them). I do each body part once a week: 1. chest, delts, triceps; 2. abs; 3. legs; 4. back, biceps. You could probably go through all that in 4 or 5 days, but I'm old. Do some cardio, 20 or 30 minutes each day too.
Eat lean meat like chicken and lowfat ham, lofat beef, tuna, etc. Eat a lot of vegetables to get full instead of loading up on carbs. Don't deprive yourself of carbs either though, eat enough good carbs, but beware of making carbs your main source of the volume of food you eat, (especially as you get older). Especially because carbs are the main thing that seems to satisfy hunger. I think a lot of people are sort of addicted to carbs, meaning that their body gets used to a ton of unnecessary sugar. Eat good carbs, like brown rice, oatmeal, etc., but beware of overdoing it.
Good products: "Worldwide Pure Protein" shakes: comes in a can, 35 g protein, only 160 calories. Expensive though, like 3$. Better option: make your own shakes with milk, protein powder, a banana. I think Creatine is a good supplement, I've used it off and on for a while, it seems good, but honestly I have no idea what it does. A lot of GNC stuff you're probably just feeding the fishes, but maybe it's a placebo effect, I don't know. "Pure protein" bars are good, I like the blueberry and strawberry shortcake flavors.
