ELITE PERSONAL TRAINING
1) Use a wide variety of weight poundages. A wide variety of pounds means a wide variety of repititions. Do not stick to doing a set of 8-12 reps all the time. Sometimes you should do sets of lower reps to keep your strength up. This will help you build more power which lets you use greater weight for your higher rep sets as well.
2) Stick to the basics. Many people in the gym will try to hit a muscle from every possible angle or try to change exercises every week to "shock" the muscle. This theory may work for a professional bodybuilder, but for most people simply increasing the weight load regularly will shock the muscle plenty. There is no reason to stand on your head to do curls or anything weird like that. Stick to the basics. Most of the best bodies you see were built on that principle.
3) Learn correct form. It is both dangerous and less effective to do things improperly. The better your form, the more quickly you will improve.
4) Use enough weight to properly work out each muscle group. Some muscle groups are a lot stronger then others. Legs are obviously stronger then shoulders for example. Use enough weight to stimulate the most possible muscle fibers in that muscle. If you go too light you should just go home because it really isn't doing anything. This does not mean to go so heavy that your form suffers.
5) Training Abs is not going to burn off fat around your stomach. There is no such thing as spot reducing fat. Fat will burn off from the whole body. The abdominals are some of the smallest muscles of the body which means that they burn off some of the smallest amounts of fat. For example: If you trained legs for three months with weights it would actually burn more fat around your stomach then training your abs the same amount of time. This is because the legs are much bigger muscles and require more energy.