Reducing your balances on credit cards and other revolving credit accounts is likely the better option to improve your credit utilization rate, and, subsequently, your credit scores. Consistently making on-time payments against your debt will also help you build a positive credit history, which can have additional benefits for your credit history and, by extension, your credit scores, too.
Once you have your credit reports, read through them completely. If you have a long credit history, your credit reports might be several pages long. Try not to get overwhelmed by all the information you're reading. It's a lot to digest, especially if you're checking your credit report for the first time. Take your time and review your credit report over several days if you need to.