It seems to me that the most aggressive players who also bluff constantly usually turn out to be Russian. Don't be intimidated by these kinds of players, just be patient, but make sure you flop the nut because these players also seem to have uncanny luck with the river.
Poker involves all the playing styles possible. Anyone that doesn't want to play against a particular style is limiting their game and will hamper their development. (Granted .. sometimes it's preferable to play at softer tables ... but do this always and you'll become soft)
Anyway ... online there's not much in the way of tells, all just stats and numbers. But! hover over your opponents who are in blind(s)\button and you'll see my favorite online tell .. "Nationality: Russian".
Our Russian friends will put you to the test so make sure you're playing comfortably within your BR.
Not good russian players play big donk agresiv poker and ewery win whit donk cards not good this fish on tabble