1.e4, develop quickly and open the center.
White opening for low rated player

As white, The italian game. Learn a few variations for the opening.
As black? response to e4, play the elephant gambit. (e4, e5, nf3, d5)
Response to d4, maybe albin. tarrasch or chigorin is good too.
These are my main openings tho

E4 and stop playing blitz and bullet. If you give yourself time to think then your openings will take care of themselves. Rapid chess is for the amusement of good players. You're not quite there yet. Take a look at the ChessMentor opening courses here:
http://www.chess.com/blog/webmaster/free-chess-mentor-courses

Definetly the open game - the most important part for you should be to understand the basic principles behind the classical openings so you can develop as a player. You can alternatively choose some off beat lines that are offered here, but they will not help you develop, so later you will be stuck, although you might have a small increase now.
For black vs 1. E4 go for the open (e5) The Spanish is rich in positions so you should want to play that - find a line there that suits you. For other openings over time your will get a sense to play them,
For black vs 1. D4 go for the QGD(Nf6, e6, d5 move order) If you want to be more aggresive there, i suppose KID is okei as well, because it is rich in positions.
For white, go for the Spanish, maybe Italian is alright as well
what opening would you recommend for a player in the 600-700 rating lvl? i have been playing some kind of king's indian attack structure for a while but i think my skill level is not good enough to convert my matches to win. i feel that my win rate with white pieces is too low and i actually feel that i play better with black pieces.