To improve your chances of having your requests approved, we strongly suggest you read this information on what to do Before You Request. You'll find helpful hints about how to fill out your Profile and links to what publishers are looking for when they approve requests.
You are more likely to be approved for future requests if you provide meaningful feedback about the books you've already read via NetGalley, too. You will see a feedback button in your NetGalley account for all titles you've downloaded.
Remember that publishers receive many, many requests for titles and cannot approve all requests that are received.