in loose games is not a very good play due to the fact that 2 of the reasons the semibluff is good is that 1 your opp will fold. this is not the case in a loose game. 2 a scare card comes out your opp is more inclined to keep you honest and call. So the only way to win is make your hand. On the flip side, you need to bet your draws so that you can get paid off when you hit them. The fact that the game is loose also causes you to be careful with your "good" hands against many players.
In a tight game you need to semibluff/bluff more and really play your draws as cheap as possible. Your draws will not get paid off when you hit them. Also your good hands loose some value due to the big hands your tight opp are playing.
Position, most of us know that this is very important, we get to see all the action that is happening before us. this is something i am working on and have been doing this. The first thing i factor in before the hand is dealt is my position at the table, I use this as a main factor before i even concider my hold cards, this keeps me from playing "calling" the specualtive hands out of position. One other thing to remember is that you do not have to be in the cutoff/button to get position, If you raise you can get position on the table by making those after you fold. Now rember that is is eaiser to get 1-2 people to fold than 4-5 people.