Is there a way that you can ensure being difficult to predict at Poker? For example, if you never bluff, people will eventually get to known that and it will reduce your ability to profit from good cards? Anyone there knows techniques or trick to avoid being easy to read?
I'm sure you are talking about Real life Poker right? because it is stupid to expect about our emotion on bluffing to be known by the computer online 
Anyway , There is no such thing unless you know how to divert your emotion from tense to happy, and from normal to abnormal.
Probably, you can't show emotions or chat but I think it's possible that you will type and type just to confuse the other players but in real life poker I think changing behavior from time to time would help you not to be read by other players. I think one of my weakness is having trouble reading others maybe they're using that trick to confuse me.