For starters, if you can't do a dip on your own, you really need to work up to it. Try bench dips at first, but you really need to do regular dips with assistance if there is a spotter available to you. Doing dips is not a trivial movement. In order to put all the emphasis on your triceps, there are a few things you need to keep in mind. First, you need to keep your body in a straight line, perpendicular with the floor, for the entire set. You can do this by putting one leg in front of the other. This does not mean crossing your legs. Try to make believe that you are stepping up some stairs. Now, you want to hold your legs in a position with one leg on one imaginary step and the other is on the next step up. You might look goofy, but if you're the guy with big triceps, everyone will be doing it before too long.
Keep your head up, and look straight ahead, so that your back doesn't round. If you're still having trouble with getting your body lined up, try contracting your abs during the set. As far as the depth of a rep is concerned, I think that going to the point to where your triceps are parallel with the floor is sufficient. Any further than this, you risk putting too much emphasis on your shoulders. Now for the good part. After you have learned how to correctly do a dip, and you've practiced a little while, you can go to bending and crossing your legs during the set. Once you've mastered dips with just your body weight, you will need to start doing dips with additional weight. This can be accomplished by obtaining a weight belt with a chain connected to it. I recommend using dumbbells instead of plate weights simply because the more weight you use, the more plates you will have to use. Plates tend to be very bulky and uncomfortable, whereas dumbbells are more convenient to tote around and easier to handle during your set. Plus, to me, dumbbells seems heavier than plates, this way you don't have to carry as much weight to the dip bar with you. No matter what, keep your form perfect with whatever weight you use. If you are to the point where you can use weight, I think that you should still warm-up with bodyweight first.
Next, you will need to do some kind of overhead extension. For some reason, many people have a real problem with this type of exercise. It can be difficult if you try to over-think the movement. This exercise can be done with either a barbell or a dumbbell. If you are using a barbell, you need to start with a narrow grip, about 3-4 inches apart. Start with the barbell over your head. Bend at the elbows and let the weight down to the back of your neck. You should not touch your neck with the bar, stay about 3-4 inches from it as a matter of fact. When you extend your arms, push up and slightly out at the same time. Your elbows should never move throughout your set, this is the key to targeting your triceps. They should always point directly up to the ceiling. Now, with a dumbbell, start out at the top, come down and across your head, but don't hit your head with your forearm. The head of the dumbbell should end up on the opposite side of your neck, behind your head. It's more like your hand goes to the side instead of straight back with a barbell. When you extend your arm, follow the exact path as the negative. Never move your elbow at all.
Next, you need to do some lying exercise. I recommend doing lying triceps extension, however, many people like close-grip bench press. For lying triceps extension, use a barbell, lie down on a flat bench, and hold the bar with a 3-4 inch grip. Start out with your arms extended. Lower the weight to the top of your nose, or even to your eyebrow line. When you extend, push the weight up and slightly out so that the weight ends up inline with the top of your head. Remember, never move your elbows, they still point directly up at the ceiling. If you choose to do close-grip bench press (which is also a very good mass builder), you need to hold your hands about 10-12 inches apart. Some disagree with this, but I really think this wide of a grip will save your wrists from injury. The actual rep should be just like a bench press movement.
Finally, for finishers, do some kind of cable pushdown. I think you should use a straight bar, and hold it with a 6 inch grip. You could use an EZ bar or even a rope. Start with the weight inline with your chest, and elbows pointing straight down at the floor. Your arms should never bend so far that your elbows come upwards. Push the weight down and slightly away from you. Keep your body very slightly bent at the waist, but never rock your body during a set. You can perform this movement with either an over-handed (pronated) grip or under-handed (suppinated) grip. If you choose to use a rope, you need to push your hands away from each other at the bottom of the rep. Either way, this exercise will blast your triceps. Here's a tip: if you are having trouble getting the inner head of the triceps to grow, try holding a straight bar with your hands about eighteen inches apart with a pronated grip. The key to a good triceps workout is to squeeze as hard as you can at the end of every rep and stretch constantly. Never, ever move your elbows, EVER! Here's a very good workout, if you're in need:
- Weighted Dips 15, 15, 12, 10
- Overhead Ext. (Dumbbell) 12, 10
- Nosebreakers 10, 8
- Pronated Cable Pushdowns 12, 10