It’s rare today to hear an absolutely flat drum sound on a modern recording. We’re always looking for ways to make certain parts of a drum kit (e.g., snare drum, kick drum) stand out in a mix without ending up with volume levels that can cause clipping.
On a snare drum, you can add a small boost at around 80-120Hz if the snare sounds a bit thin. A boost at around 5-8kHz adds some nice high-end presence. Kick drums often benefit from boosts in the 60-100Hz range if you want a solid thump, while boosting between 100-250Hz can add overall girth. Avoid boosting anything in the area from 250-800Hz, as this will tend to sound muddy, while boosting frequencies above 8kHz typically just adds hiss. If you are close-miking the kick drum pedal, a boost at around 3-6kHz can add a nice snap to the sound.
For hi-hats and cymbals, you can lower (or cut) the amplitude of frequencies from about 250-800Hz to reduce overall muddiness, and roll off everything below 250Hz steeply, as few cymbals have any energy that low. To add some additional clarity or “zing” to cymbals, you can try boosting frequencies from about 3-8kHz, while frequency boosts all the way out to roughly 15khz can add a lot of overtones, often referred to as “sizzle.”