One of the most effective ways to improve is to model your play on a well-known player, whose style appeals to you and appears closest to your own abilities. By adopting most of his opening repertoire, you can ensure yourself a set of openings which accords with your style, and also have a steady source of material to study.
If you like answering 1.e4 with 1…e5, then Ivan Sokolov is an excellent model to follow. He himself attributes the formation of his style to having studied game collections by Alekhine and Keres in his youth. Both were classical open games players, and Sokolov has followed in their footsteps, almost always meeting 1.e4 with 1…e5, which he knows and understands inside out. I recall at the Gibraltar Open a few years ago, when I was working as Press Officer. We had trouble deciphering the scoresheets of one of Ivan’s games, so the next morning, he kindly went through the game with me, so I could get a correct PGN for the website. In the process, he talked me through the game, which was a virtual master-class in the relevant 5.d3 Lopex, which had occurred in the game.
Here is another excellent performance by Ivan, on the black side of the Spanish, a game which was instrumental in his winning the 2012 Reykjavik Open. His extremely strong opponent is in trouble from quite an early stage, as Ivan gives a classic demonstration of how Black should play such structures, after the double pawn exchange on d4.