Nutrition, Nutrition, Nutrition. Nutrition is the key factor when looking for improvements. Without it, you will see 0% progress. Why? You workout 1-2 hours per day (at most). And most of the time, 5 days a week. Unless you are insane and doing 7 days.... like me.
Eating > Exercising (Time Wise): You eat at least 3 times a day. You should be eating 5 times a day. Nutrition is all day so its no wonder that it has more of an effect on you.
You Are What You Eat: If you eat french fries, burgers, and all those foods high in fat. Guess what... you're going to look like a fat ass. If you eat healthy foods such as vegetables, lean meats, whole grain products, oatmeal, basically non-refined foods, you will look healthy. Catch my drift? You can't eat off the 'Weight Watchers' menu at applebees everyday and expect to see results. You need to work hard to look good. Rotate your fridge... throw away that sugary cereal and eat oatmeal. Replace those kashi bars with apples (high in fiber).
Push Yourself... REALLY Push Yourself: When you are at the gym, make those last 3 reps count! You should be struggling on those last reps. If you can crush all of the reps in each set, increase the weight. Also slow movements to success. What the **** do I mean by that? Perfect form! Slowly perform the pushup, pullup, curl, press, whatever and make sure it is perfect. Your goal is to KILL your muscle cells. You can't do that by speeding through the routine.
Keep That Heart Rate Up! Spend less time at the gym talking and more lifting. You can talk about women, drinking, and Modern Warfare 3 another time. When you are at the gym you need to focus and keep that heart rate up. Do a few pushups between sets to pump up that heart rate. Keep rests to 30 seconds.
Also here's a great chart to follow, rep-wise:
Goal -- Reps
Lean 12-15
Toned/Broaden 8-12 reps
Bulk Up 6-8 Reps
Remember make the last 3 count!!
Generally, 2000-2500 calories is where you should be at to maintain your weight, depending on your height. Do not go more than +-500 calories on your calorie target unless you are a bodybuilder/wrestler/gymnist/etc..
Good luck!