First of all, use the mouse with the crosshair and mouselook on.  To turn these on, go to the console (~), and type crosshair 1 then enter, +mook, then enter.  Got that?

STRAFING

    Now.  Strafing is an invaluable skill to have.  HOLD the ALT button and press left or right to sidestep or "strafe".  Circle strafing is fairly difficult to master.  Press , to strafe left, or . to strafe right.  Then while holding one of the strafe buttons, move your mouse the opposite direction, in a big circle around your target.  This is Circle Strafing.

    To rocket jump you'll need the rocket launcher, some ammo, and more than 60 health (or you may die!)  first, figure out where you want to jump to, point yourself in that general direction, run towards it, use your mouse to look down, and press jump and fire almost simultaneously. (jump first.)  This can be used to reach otherwise unreachable places.  You can jump close to 6 times higher than regular.

    A backward rocket jump is the same thing, it just propells you further horizontally.  Just do a rocket jump running backwards.  The higher the angle you're aimed at, the further you'll go.

If you don't get it, watch THIS demo. To run it, go into quake, hit ~ then type "playdemo sprjstra" and hit enter.  Make sure it's in your quake\id1 directory, or it won't work.