Playing tips

I will take it for granted that you know how to play Dm on the internet. Here are a few tips that might help you to be closer to the top of the frag list.  
 

Number two
Practice, practice, practice know were everything is in the map you are playing and how to get there, most maps have several routes.

Number three

Rule number one and two are the most important .
 

Circle Strafe Circle strafing is the single most important fighting technique you need to know. Using the left or right strafe keys, you circle around your opponent while always facing towards him. Use the mouse to keep your crosshairs on the enemy, and you'll be able to fire on your enemy while you're strafing. Most enemies won't be nice enough to stand still while you're circling around him. You'll have to adjust your technique. You don't even have to strafe in a circle. Eventually you'll learn to start strafing left and right randomly as well as moving forwards and backwards while strafing. Don't let your movements become repetitive. Good players will pick up on your patterns. Try switching it up once in a while.

Don't whine  nobody likes to hear it if you are getting wiped and you don't like it, do one of two things put up with it and learn, or find a different server (rule two may in order huh) if they all have really low pings than you why did you go there. IF a lpb (LOW PING Bastard) shows up and is killing everybody with the rail gun tell him to change weapons or leave but don't wine.

Run Backwards If you're outgunned and running low on health, don't be ashamed to run away. When you do run, run backwards. Running backwards allows you to shoot at enemies while you're running away from them. Using the rail gun while running backwards can be very effective because you know that your attacker will be following you. Run through a doorway, and you can use it to frame a nice rail shot. Firing rockets behind you will also make your opponent think twice about pursuing you. The grenade launcher works nice also. In order to run backwards effectively you have to know the level well. You don't want to get stuck in a doorway or accidentally fall into the lava.

Timing ex. how long until the Triple damage respawns.

Choke points places in maps were people tend to group up, you can get kills by say the rocket launcher shot into these areas even when you don't see anybody.
Also know were people tend to camp (sit and wait for you) you can often kill them by shooting in these spots before you know they are there. I hope you are not one of those campers remember rule number 1

Know the weapons and when to use them, ex. don't use the rocket launcher in a  small closed area splash damage can kill ya. The rail gun is a better choice at long shots than say the shot gun but up close it is the other way around.

Learn the timing of weapons how far to lead a target, this can take a lot of time depending on your lag or lack of lag on the internet.
The higher the lag harder it gets.

Try to find a game that has players with   equal ping time as your self.
Trying to hit a player that has a 50 ping when you have a 400 ping is a real trick especially if that player is of equal or better skill than your self.

Configure your keyboard so it is easy to zoom and also to hit what ever keys you are using without looking.
I like to use the mouse and keyboard, the mouse for aiming and firing and the keyboard for movement. Also keep them clean, mouse, pad and keyboard.
There are many different joysticks out there I have yet to try one that works as good as a mouse. Manufactures send me one and I will try it, always looking for a better mouse too (hint, hint)  Try to keep your mouse clean. Every month, or whenever your mouse starts feeling sluggish, open up the bottom of your mouse, and scrape off all the junk on the rollers.

Your mouse pad is also important piece of equipment. A good mouse pad ensures that all your mouse movements actually register on the mouse. I recommend the 3M Precise Mousing Surface or the Everglide mousepad.

 The 3M PMS is very thin; it's almost like a skin sitting on your desk. It has a nice textured surface for gripping the mouse ball, but the pad tends to wear out after a few months. The Everglide is much more durable than the 3M pad, and it also features a textured surface. It takes a while to get used to the ultra-smooth Everglide, but it's worth the time investment.

Learn to fly and shoot, Quake3 has jump pads don't just use them to get to places.
While you are in the air look around for player and shoot (ex. the q3test2 map the triple damage is on the high platform people tend to camp there because its hard to kill them from down below, but if you jump on the pads and go up shooting before you land you can often surprise that player by killing him or her )(fun fun).

Spin on a dime and keep moving  What I mean is when you are being chased do a 180 turn and run backwards and shoot at the chaser. After some practice you will be doing this even when nobody is there its a quick way to find out if you are being chased and shoot first. The higher the mouse setting the less you will have to move it and the quicker you will become a snap turn and shooter (what fun).

Locate the sound it helps to locate players and items. I find headphones help because I can turn them up and not bother everybody else when I am playing.

Increase your frame rates set your computer up so you are getting at least 30 fps {frames per second} you can do this in the setting in the quake 3 menu, start by turning of video options that you could live with out {ex. shadows, marks on walls } if you still need more frames drop you video resolution. If that doesn't work maybe it is time to upgrade your video card, maybe the CPU.

If you are number one for a few map cycles leave  The reason is you are not going to increase your skill level by playing people that aren't as good or better than yourself. Sure it is fun being number one, but if nobody is close to you in frag numbers it will get old fast.