Depends on the player really.
Established superstars - Praise them to indicate my intent, see their reaction. See if I can unsettle them enough to make them interested in a move. That way you can occasionally force down the transfer price when otherwise it would be astronomical.
Youngsters - Scout first to try and see if they've got good potential. If they have then sometimes I try to unsettle them as above, depends on how highly their club values them. Mostly though I just steamroller in with a high bid, mostly I end up paying over the odds though then find out they're crap and sell them for peanuts 2 years later.
Standard players - Bid low and increase until it's accepted. Normally though I've got 3 or 4 players I'm interested in buying in this kind of situation, so it's a case of start the bids low and see which team breaks first and accepts. Often I'll keep raising bids until several are accepted, then see what happens at the negotiating table. In this case, player's wage demands could be a factor in which one I go ahead with.