Quote Originally Posted by celtic123
Jh 10D 6S

The BB calls 3xBB.

(...)

Then to make matters worse everyone limps.
Your post is kinda hard to read, I think you mean to say he bets 3BB (gross minbet) and everyone calls? (limping is calling 1 BB preflop)

About putting people on ranges, it's not an exact science, it's already a good first step that you're thinking about it. On the flop you could for example say to yourself, he might have a J, a T, or a drawy hand like 98,87,Q8. Or well, just A high - I means he bets so little it could be anything, also a 6. On this flop a lot of hands will either have a pair or a gutshot or just some overs they don't want to fold for that price.