IMO the meat and potatos of triceps are pressing, pressing, and more pressing. Bench heavy, close grip work, close grip incline is ridiculous on the triceps, strict standing overhead pressing is hard on the triceps, etc. Now about extension work... including pushdowns, skull crushers, etc. I like extension movements, but IMO keep them light and keep the reps higher. Extension movements are rough on the elbows. I consider them to be much better for high volume movements, and it's with these movements that I'll employ supersets, etc. Besides, things start to hurt when you skull crush 225. If your elbows don't hurt now when you skull crush heavy they will when you get older/bigger/stronger.
The other thing to realize is that since you're 167lbs, you're going to have to gain some weight to really make the triceps come out. I'm sure you know that, but sometimes the easiest thing to do is right in front of us.