adding a few things to this very generalised thread.
the time factor isn't one you can really trust, unless you know the opponant very well. lets say you are playing a heads up match, you have played the opponant before and tyhink you have picked up a timing tell. you also know he only plays 4 tables at once and this timing tell has been observed over many hands. ----- that would be something that constitutes getting reads with time, anything else is just guesswork which is usually used to make yourself feel better about bad plays.
statistics are gold. you can use certain programs that tell you if they are winning or losing in a certain game. this is invaluable information as you can make some pretty damn accurate assumptions from this info.
as other have said, betting patterns is huge. try to get in their head and work out why they are raising 5x with QQ+ and only 3x with everything else, are they scared, they may have been screwed over with these hands before.
if you play certain players often, like for instance if you play sng and seem to be on the table with the same players, you can use a hud to go over their play, review hands that they have played in, to get a much better sense of what they are about. this is really important if you want to crush games. if it's a mtt you play, your likely to not see these players much at all, so dont bother.
theres more, but i cant think of any.
