How to beat a strong master, if you have 1900 ELO points and you have to play with him in a chess tournament? First, do not be afraid to play aggressively. Do not play passively. Try to attack and replace the pieces, keep an active position and try not to make silly mistakes.
I would like to show you a game my friend Paweł Gulik(1915 ELO), in which young uncompromising chess player defeated a strong International Master Evgeny Sharapov(2509 ELO). They played Gambit Benko/Volga.
10. h3 Nb6 {very active move} 11. Bf1 Bb7 12. Bf4 a5 13. Qd2 a4 {White has a very active position} 14. Rab1 Ba6 {Black want to exchange a passive bishop and play his knight on c4} 15. Bxa6 Rxa6 16. Bh6 {White has a deep plan. It is based on the exchange of Bishop on h6 for knight on c4, for the price Bishop White has a free diagonal a1-h8 and can play e5 and try to open a e line for his own rook with the attack on e7 pawn. Queen will be very active on c4. Stands better than c1. White has the initiative.} Nc4 17. Qd3 Bxh6 18. Qxc4 {Attacking the pawn on a4 and rook on a6.} Rb6 19. a3 Nd7 20. Nxa4 Rb7 21. e5 Bg7 22. e6 Nb6 (22... fxe6 {is worth consideration} 23. Ng5 Qa5 24. Nxe6 Rf5) 23. Nxb6 Qxb6 24. exf7+ Rxf7 25. b4 {Black position is shaking} Qb5 26. Qe4 {Now White can capture pawn on c5} c4 27.Rbc1 Rf5 {Sharapov thought that the opponent will kill on c4 and he on d5. Qe6+ was a surprise} 28. Qe6+ Kf8? 29. a4! {brilliant move} Qxd5 {The position is lost. The last attempt is Qd7 Rxc4 Qxe6 dxe6 Bf6.The opponent did not provide that after Qc8 + Kf7 Rcd1 black Queen has no escape. C6 is controlled by the white Queen}
30. Qc8+ Kf7 31. Rcd1 Qxd1 32. Rxd1 Rxb4 33. Nd4 Bxd4 34. Rxd4 Rxa4 35. Rxc4 Rxc4 36. Qxc4+ Kf8 37. g4 Rc5 38. Qd4 Kg8 39. Kg2 h5 40. Qe4 Kf7 41. Kg3 hxg4 42. hxg4 Re5 43. Qa8 g5 44. Qh8 Ke6 45. Qh6+ Kd7 46. f4 gxf4+ 47. Qxf4 Ke6 48. g5 Rf5 49. Qg4 Ke5 50. g6 Rf8 51. g7 Rg8 52. Qg6 {and mate in 14} 1-0