I agree with Mr Mcj about creating the TAG image cos when you hit a run of cards and keep raising, betting, raising etc. people can get restless and occasionally showing them a good hand will put their mind at ease somewhat and when you pick up 72 and smell weakness there's a good chance you'll be able to steal the pot based on your current image.
On the topic of giving away information, that is inevitable but if you mix up the play with the hands you show (ie. play the subsequent top 2 pair differently from last time when you showed it). Obviously i wouldn't overdo the showing cos they will pick up too much information but on occasion it can be quite a profitable play.
On the flipside, showing a bluff (which by the way i VERY rarely do) has its advantages. If there is a player at your table you reckon is a bit volatile, a bit of a loose cannon, you can get them on tilt bigtime. it'll hurt their ego and they'll come back at you, trying to do the same to you as what you did to them and very often you'll have the chance to break them.
I think both in moderation can be very useful but definitely don't overdo it, find the right balance to manipulate your table image.
and breathe....
