As Monty advises, stats are important, invest $55 in Pokertracker - its pretty much cricuial and youll never look back.

Id estimate 5-10% are students that study the game. About 10-20% of players seem to have the winning styles (TA's, SLA's and UA's etc) though some of these will develop the style naturally, some will have also researched.

Good luck, keep within your BR and study your game and your ops and 'the' game and you should be fine