There's so many betting patterns.

My favorite to detect is a flush draw. There's a bunch of lines flush draws take, and I can sniff out a lot of them.

I'm not good at sniffing out if my 2nd pair is good, or telling if that guy just rivered an ace.

But really, I think this topic has to get a lot more specific, and even then any advice would be very vague and general.

Here's a line I see at 25NL a lot. Flush draw check-calls the pot on the flop, and minbets a turn blank. A pot-sized raise is usually taking the hand.