Follow the rubric.
Address the skills (Causation, CCOT, Compare/Contrast) while answering the question. It seems simple but many students get caught up with the documents and forget that you have been asked to make an argument.
Utilize the resources given to you in class as well as DBQs listed in practice books. Use the AP Central's website to get practice examples. Practice reading the docs
Make sure you compare AND contrast or address continutity AND change or cause AND effect
The DBQ is worth the greatest amount on the AP test. Spend time reading the documents but also take time to outline your essay - make a plan - will help with flow and argumentation