Focusing on a rating is not the best way to become a better chess player. Also, picking one opening or another is not the way to improve. A better goal would be to improve your understanding of basic opening principles.
What is the best way to do this? Stop playing bullet and blitz. Those encourage young players to develop bad habits that only interfere with your progress. Stick with slow time controls.
is there an OTB club in your area? If so, join it. Find players there who will discuss your games afterward.
Another recommendation is to study the classic books that provide instruction in opening, ending, and middlegame planning. A month with some classic instructional books is more helpful than a month of playing blitz or bullet.
whats your current elo?