Most test takers who take the GMAT for the first time are often frustrated and/or concerned with their initial results. This is completely normal and should be a wake-up call about the GMAT. It is long. It is challenging. But it can be conquered!
Here are some ideas for improving your initial GMAT score:
1 - dedicate several hours to reviewing each question that you missed on the practice (or real) GMAT exam (if you download an exam report, you will typically only get a high-level readout of where you did well or poorly).
2 - following your review, identify your weak areas and focus on those areas when you train on your own.
3 - continue practicing problems of all types in order to ensure that your approach is balanced. Scour the internet forums for alternate solutions to problems that pose difficulty.
4 - seek help. As a Wyzant tutor, I seek to coach prospective Business School students on the strategies and tactics for achieving success on the GMAT. My students have seen 130+ point improvements by relentlessly focusing on their weak areas and adding structure and discipline to how they tackle this immensely conquerable test.
Hope this helps!