A dumb thing to do if you are playing in an arena with self-damage turned on. The best tactic if you have a normal mouse is to flick the mouse so you are pointed at the ground and slightly behind you, jump, almost immediately fire the rocket launcher, then flick the mouse back up and bring your enemy or your chosen destination into sight. I've heard that the flick/fire method is impossible with those kewl optical mice; perhaps someone with practice on those can post their tactics later.

Some pointers:

  • Don't overuse rjs: When a player gets around a map solely by using rocket jumps, something's wrong. This is railbait. While in the rocket jump, it is difficult to move yourself quickly; that nice parabola you make is just right for someone to whip out their railgun and give you a hot depleted uranium injection.
  • Keep yourself oriented: If you are rjing a whole lot, you can easily forget where your enemy is, or (in the space or lava maps in Quake 3: Arena) where the ground is. Rocket jumping into a lava pool ruins your day. Try to avoid it.
  • Keep in mind that falling damage may be turned on: This is very common in Rocket Arena 3; the arena may have self-damage turned off, only to surprise an unsuspecting deathmatchers with a large deduction in health when they rocket jump off the equivalent of a eight-story building. You should practice the rocket landing; just before you hit the ground, fire a rocket. The explosion will cushion your fall, and if done correctly can propel you at high speeds. Fun stuff.
  • Get good at the rj/rail combo: This is a great combination of weapons. Rocket jump, and while your opponent is searching the sky for you, switch to the railgun and give them a taste.
Defenses: So you're dm'ing, and some schmuck is using his leet rj script to make your job (that is, turning him into gumbo) harder. Here's some ways to stop his hopping:
  • Railgun: A bad rocket jumper will just let him/herself fly through the air with grace. This pretty parabola is pretty slow, and more importantly very easily predictable. Get out the rail, put the crosshairs where the apex of their jump is going to be, and point and click. Best case you get a rain of gibs, worst case you knock them way off course.
  • Rocket Launcher: If you're not so good with the rail, try estimating when & where he's going to land. Apply rocket. Rinse, lather, repeat.
Advanced Topics:
  • Getting around the map with a quickness: Flick the mouse, but angle the rocket at more of a 45 degree angle to the ground and opposite of the direction you want to go. Timing this like a slow bunnyhop, you can cover a lot of distance really quickly.
  • RJ/wall combo: If you've got a platform you can't quite get up to, but it has a wall with some protuberances coming out, rj up to those, then rj at an angle, towards your intended destination, off of the wall. This is pretty difficult, but you can also use this to go in random directions off a tall wall in a firefight.