I think there are lots of ways to read players online...
-Sometimes their name and their picture will tell u a lot about them.
-I watch for betting patterns, pay attention to anything they write in the chat window and notice whether or not they use the auto-select for action or not. If they don't use the auto-select buttons, I notice how long it takes them to act. Sometimes if they play very quickly or if they auto-select it means they are playing in multiple games or distracted. Either way, it tells me that they are probably not paying full attention to the game or they only play the cards/position.
-Noticing how much they bet or raise and when is also a good indicator of what kind of player they are. Do they take advantage of position? Do they go all in? Do they bet or raise random amounts?
-If the game is quiet, I'll try and start conversations. I look at the way they spell things, write things and then of course I pay attention to what they say/write. Are they cocky? Easy to ignite on tilt? Do they even engage in conversation with me? Male? Female? etc.
That's my .25
i find it hard to read people online also. just when i think i have figured some people out it seems they move me to another table
Make reads and then trust them, that is the ultimate way to go forward. Play frerolls or free money games and just spend time putting people on hands. Play low buy-in tourneys and now that you will go out if your read/ logic is not correct.