Opening theory, middlegame strategy, endgame technique, and tournament preparation.
Know something useful about chess?
Post insightControl the center (e4/d4), develop knights before bishops, castle early, connect your rooks, avoid moving the same piece twice. These five principles will outperform memorized theory against 95% of opponents below 1800 Elo because they will deviate from book lines by move 5 anyway. Study openings after you stop hanging pieces in the middlegame — not before.
Per multiple chess improvement studies, players who exclusively play blitz (3-5 min) plateau earlier than players who balance with rapid (15+30) and classical (30+) games. Blitz reinforces pattern recognition but trains you to skip calculation. For improvement, play at least 2 rapid or classical games per week with full post-game analysis. Use blitz for fun, not growth.