The drums is one of the most important instrument in the contemporary music wich is based on rythm, in certain genres (such as rock) a solid rythmic base and well done may be worth half the song.
The main instruments in the drums are the kick, the snare and the cymbals, the snare above all is the most important instrument in the rock drum.
Even if percussive each instrument in the drum lies in a definite part of the spectrum and the aim of a good mix is to avoid that the different frequency of each instrument overlap too much creating confusion and muddyness.
The kick occupies the lowest part of the spectrum, usually the power of this instruments is in the 70 - 80Hz range, to get a clean sound we can apply an eq with a Q of about 1 and a value of -3 to -6db in the 400-700Hz range to remove the cardbox sound, the if the lowest part is to uncontrolled and boomy a hi-pass filter can be applied at about 40 - 50Hz, you can also use some gentle eq above 2-3khz to brighten the sound.
After eq is compressor time! Use slow attack time of about 15-25ms, ratio of 4-5 and short release time, the shortest available (usually 1 or 5 ms), this way we can bring out the explosive character of the instrument lowering the level of the boomy tail, if you prefer a BIG kick just give gain to the compressor so that the tail is louder.
On the kick usually there are no reverbs, if you want to try use a reverb with an high pass filter because reverb on the low frequency range sound boomy and chaotic.