There is a lot of information in this forum about strategies. Please take time to read through those. It would be very helpful.
Here's what i recommend.
1. Start off with solving Official Guide problems. Then solve the ETS test papers available from GMAC's website.
2. Monitor your performance closely by studying your errors and learning how to avoid them.
Participate in the Online Math Challenges
held right here on GMAT Club.
4. Improve your concepts by solving tougher problems.
5. Take practise tests ONLY to improve your timing. Dont worry about your test scores.
Finally, dont look to judge your performance based on statistics such as i got 10 out of 15 right ..etc..etc. .. We should measure our performance using metrics like : What did i learn today OR am i repeating the same mistakes over and over? OR How well am i doing under timed conditions? etc.etc These metrics are much much more valuable in prepping than just keeping statistics.
The goal is to develop a learning model for your prep where you adapt your prep depending on your specific needs.
Hope this helps