GMAT 310

That's going to be tough, but it depends a lot on why you're getting that score. Did you run out of time before completing one or both of the main sections? There is a substantial penalty for not completing questions, so if you did time out you will get a big jump just by speeding up and guessing at the end.

On the math side, if you knew all this material well once upon a time but you have simply forgotten, it's not always too hard to get back up to speed. However, if some of these concepts were always a struggle, it might take a bit longer to improve.

In verbal, learning and practicing new strategies can certainly make a difference, but if it takes you a long time to read and comprehend, the improvement process can be a long one. On the other hand, some people find that they simply need to focus their attention differently. For instance, maybe you are getting stuck on small details instead of reading for the larger point.

I can give more precise recommendations if I know more about your experience, but in any case you should start right away with a full prep program and see what you can do. There should certainly be many areas in which you can improve your performance!