Hi ivgj,
When you scored 500, what were your Quant and Verbal Scaled Scores?
Putting together the exact combination of resource to help you hit your goal will be a little tricky, since we don't have a clear idea of your strengths and weaknesses. By studying off-and-on and not putting in a consistent, serious effort, you don't have reliable data to compare with. You probably have an idea of your "weak" categories, but we don't know the specifics.
To raise your score 200+ points, you're likely going to need to invest in a class of some kind (Guided Self-Study or Instructor-Led). Tutoring might be helpful later on, when you already know what you need to focus on, but is probably not a good idea to start with (since the tutor will have to spend time trying to figure out what you need). You're also going to have to put in the consistent study time needed to succeed. Most Test Takers spend 3 months (or more) of consistent study time on the process; during that time, it's common to spend 10-15 hours per week (or more) on your studies.
GMAT assassins aren't born, they're made,
Rich