All electronic equipments need to be optimized and that applies to the Nikon D90 as well. This include recommended picture control creation, Fn button function assignment, lens filter usage, ISO limit set and image format set.
In my experience of photography, the use of external flash unit on the Nikon D90 is also highly recommended for bounced lighting for indoor shots.
Based on the pros, a unique set of new picture controls can be easily created under the menu of the Nikon D90. This brings instant recall capability to use the right tonal settings for the shots you may encounter. Each default tonal setting - vivid, neutral, standard, monochrome etc. serves a unique purpose and use of it is highly recommended throughout your shoot. Of course, users are encouraged to play with the hue, saturation and sharpness of each default tonal setting to achieve his intent to relate each shot. The Fn button next to your camera grip can be configured to instantly allow you to call up the available tonal setting that you can almost instantly choose to use. This truly makes Nikon a one-hand shooter champion.
ISO is a big element in digital photography when most camera boasts a usable ISO of up to 12800. But in the law of silicon sensor, image deterioration occurs from beyond ISO 1600. If you are a seeker of better image quality, you would stay away from using ISO beyond 1600. This of course comes with a price that you need to balance as shots made without flash (best practice) at ISO 1600 will now require a much steadier hand or tripod.
NEF/RAW image format is always recommended as each shot is stored uncompressed. The Nikon ViewNX software or other more pros applications can help convert those winning shots to JPEG when needed.