Hey,
It's ok to fail! Most people don't get their target score in the first attempt. The good thing about GMAT is that you can practice and learn how to crack it. You have scope of improvement in both quant and verbal sections. I'm not sure what your target score is but depending upon that you should plan your strategy.
1. Keep/analyse error logs
2. Practice a lot of mock tests. Take complete tests (all sections) to train your mind.
3. Practice daily
4. For material, you can refer to some blogs that have explained very nicely here on GMATClub itself.
Hope this helps. Good Luck!