Thanks for the replies, guys.
In this example, I am UTGC, and CO is my opponent. He called my river bet, and won, as I held
![The Six of Spades [6s]](https://pofex.com/images/smilies/6s.gif)
. I usually like to go for one big bluff per session, and I felt the timing was right on this one. I had played so tight until this point - my raises were getting a lot of respect. I really like the flop - I have a chance to hit my straight. When my opponent called quickly, I knew I was beat. The turn was not my favorite card - but my opponents bet was weak - I could tell he didnt like the card either. If he had a set, he would have fired more, fearing I had a hand like
![The King of Clubs [Kc]](https://pofex.com/images/smilies/Kc.gif)
. A straight would have pumped it too. There was an outside chance he held the flush - but I didnt feel it here for some reason. I put him on a hand like TT or JJ. Good enough to just call a raise with - but not good enough to pump the pot with a lot of chips. I figured that any 7, 6 or 5 would make my hand good. Plus, there were several scare cards that could come on the river, so I could bet and drive him off his hand - any heart, an A or K.
With the A on the river, I knew I had to bet in order to win. The 1/2 pot bet here seemed appropriate - my opponent only had about 375 left now. If I put him all-in, it would of looked like a bluff - I bet 250, making it look like I wanted to be called, but still a substantial enough bet for him to fold to.
He let the clock go down to one second and called. He showed the two black queens and scooped. I couldnt believe that he called. I made a note and moved on.
My table had been playing so tight - It was very disappointing to see the one big move I had been planning go down in flames. I doubt this guy had a read on me - I just think I ran into someone that was too stubborn to fold - I guess I should have picked up on this.
D