When you play poker are you always putting people on hands and trying to find poker tells?

play poker

When I play poker I seem to always know if i’m ahead or behind in a hand and if my opponent is strong or weak – but I never put people on hands – do you? and if so how?

Also i’ve got many poker books on tells but as of yet never found a tell on someone where I no for example he covers his mouth when he’s strong – How do you get tells on people? Are you always looking for tells?

Thanks!