It can be hard to get reads on people in one SNG, and by the time you have a read on someone, you or he is likely to be eliminated.
That said, I find reads can be very helpful when you get down to 5 or fewer players (and you usually have enough hands to have some kind of a read on 1 or 2 of them).
A few things I try to pick up on are:
<ul type="square">[*]someone who can raise preflop and fold or check/fold the flop (probably plays his cards)
[*]someone who overdefends his blinds but folds easily on the flop (steal on the flop, not preflop)
[*]someone who checkraises (some people just don't...)
[*]someone who is tight but never raises preflop (if he bets the flop, he's got something...)
[*]someone who plays any ace
[*]someone who bets any pair on the flop
[*]someone who is tight early and gets aggressive when down to 8-12 BB (then I think it's one of you)
[*]maniacs (isolate)
[*]calling stations (don't bluff)
[*]someone trying to fold into the money (steal all his blinds)
[*]someone who has folded to a scare card in a big pot
[*]someone whose chat indicates he is a 'by the book' player (usually won't adjust when game is shorthanded) [/list]Of course with so few hands, these reads are sometimes wrong, but they are right enough to make them worthwhile, and if you see the same player again you can refine your read.
FWIW, I'm just a recreational player and usually play 1 or 2 tables at a time in the $10-$30 buyin range.