I'm not sure what all has been covered, but I was toss some of my knowledge out there...
Anybody who is just starting out needs to work up slowly... stretch well and do a little cardio (just 5 mins) before you start lifting to get loose and to get your heart pumping. When you are just starting out, High Reps/Low Weight is your friend. There is no point to start off with close to your max weight with only a couple of reps - 1) you are more prone to injury, 2) your muscles/tendons/ligaments aren't used to working out so you have to move them along slowly. Like I said, stick to high reps and low weight for a couple of weeks. As you start feeling stronger/have more stamina, you can slowly begin to increase your weight and lower the reps (High Reps/Low Weight = Toned; Low Reps/High Weight = Big).
Most people who just start out in the gym will really only workout 5-6 muscles (Bench, Bis, Tris, Abs, Shoulders, Back - the first 3 are the main ones you will see). This shouldn't be encourages because when you perform diff lifts you have a variety of diff muscles working, synergists/agonists/antagonists/etc. Surprisingly, if you want to max your bench press (I only mention this b/c for some reason this workout is the "macho" lift) you need to workout your legs as well. You will never reach your peak if you don't work out your entire body, and cmon who wants to look top-heavy with chicken legs?
Some of the most overlooked workouts, that are probably the best for you are pushups, situps, dips, and pullups. These need to be incorporated into your workouts somehow.
Diet - In order to achieve the results you want, you have to decide what you are going for. If you want to lose weight, you have to burn off more calories than you take in and if you want to gain weight, you have to take in more than you burn off. Simple enough... To gain maximum muscle mass, you should be eating roughly 1g of protein for every pound that you weigh (Ex: I weigh 180, so I try to eat close to 180g of protein everyday). Whey protein, fish, turkey, nuts, fruit, vegetables, chicken, wheat, and milk will become your friends if you want to have the best results, without putting on "bad weight." Also, if you are spending money on an expensive creatine, you are wasting your money. Just go out and buy GNC's Creatine Monohydrate or whatever cheaper alternative you can find. If you buy creatine, you should be taking 3-5g of it everyday. EVERYDAY, even when on rest days.
After you workout, try to take in a decent amount of protein/carbs within 30 mins of working out (afterwards). Also, try not to snack after 8pm, and if you do, make sure it is something healthy.
I'm going to guess that most of what I just said was covered, but I thought I'd toss out some of the basics things I've followed over my years in the gym.