The best "read". even in live play is betting patterns. You should pay attention to how they bet, what they show down when they do bet. Do they bet big or small with big hands, do they bluff alot, etc. etc. etc. Take good notes. It takes times but is worth it in the long run.
Some people talk about tells
on how long they take to act, however this can mean alot of dif things to a difficult decision or just acting, or they got a phone call. If someone takes longer than normal to act, note what happened afterwards, did the player have a big hand? a bluff? what?
Hope this helped some.
Main thing, pay attention to betting patterns.