LST = low stress training. what i do is to allow the plant to reach 6-8 inches in height, and tie a piece of string around the upper part of the plant and tape it to the sides of the pot. this allows light to reach the lower portions of the plant, and helps even out the canopy. you can do this as much as you want, as long as you dont break or damage it, it will only cause minimal stress if any.
FIM = "Fuck I Missed". its basically the same concept of topping except you only "pinch" or cut with scissors. First locate the top of the plant; ie the new growth tip. cut off about 80% of the new growth tip and your plant might go into shock for a week or so, but it stops all vertical growth and you can end up with anywhere from 2-8+ tops depending on strain.
Topping = the idea of eliminating vertical growth and growing a bushier, smaller plant with 2 main colas instead of one. Wait until the plant is either very healthy during week 2, or as long as you have a week or two before you flower. I like to top after the 3rd or fourth node (Uncle Ben has a very nice guide located somewhere on RUI), basically locate the node where you want to make your cut and cut with a clean pair of sterilized scissors right above the node directly through the main stalk. you can use the cutting as a clone if you want to as well.
Supercropping = one of my most favorite and useful tricks. This technique creates a sturdier stem, faster rate of growth, and a hell of a lot more budsites. I usually supercrop my plants at the end of week 1 flowering. Basically you grab the stem in between your thumb and pointer finger and apply a little pressure until you hear a small snap or feel it. dont squeeze too hard or you could cause some serious damage. What you are doing is crushing the "tube" in the middle of the plants stem that transfers essential nutrients and energy to different parts of the plant. This causes your plant to go into "overdrive" (in my opinion) and by week 3 of flowering, or whenever the stretch period ends, you should have atleast 5x as many budsites. Be warned not to squeeze too hard and be prepared for a short shock period, if any. You will know if you were successful when there is a kind of "knot" where you inflicted pressure. This knot should be slightly discolored or brown, and very hard.
hope this helps, didn't take me too long once I got started.