start with compression
-20 db threshold depending on the source
4:1 - 8:1 ratio
with about 10 ms attack or less (the less the attack, the bigger it seems)
and 50 - 100 ms release depending on the speed of hits on that particular song
after compression and getting make up gain sorted out, start with eq (eq after compression, in the chain)
cut some mids, do this with a scooped Q, try to use a good eq plugin that emulates a real hardware one, so you dont end up doing a radical eq that isnt very possible / pleasing to the ear
listen closely to the tom on solo, and start by dropping 800 hz using a Q of 3. if its starting to sound better, raise it back up then drop 500 hz and listen. compare the differences between these two and decide which is best.
some toms benefit from dropping 400 hz too, it just depends on how it was tuned, and how big the shell was...
then for small toms, add 3db - 6db boost anywhere from 100hz - 150hz
for mid toms, 80hz - 100hz
for low toms, 60hz - 80hz
use a small q for this, because wider q's will add too much bass to the toms. this will bring out the low octave of the tom's note, and pack some punch in the mix (they'll stick out!). do this individually for each tom on each tom track.
after this, you're going to need a compression bus to send all of your drums too, kick, snare, and toms. you want to aux send out from your drum track channels to this bus, and do heavy compression on this bus. make it half volume, this will fill the void and make the drums huge.
then you're going to definately need reverb to make the snare and the toms larger than life. if you dont, they're just compressed hits. reverb adds the necessary body and tails to the hits that make the kit bigger than it is on tape. do the reverb individually for each drum track (dont send from the drum compression bus!)
key bass frequencies for drum tones
kick: 60 - 80 hz
snare: 150 - 250 hz
hi tom: 100 - 150 hz
mid tom: 80 - 100 hz
low tom: 60 - 80 hz
popular frequencies for attack:
kick: 3khz - 8khz
snare: 5khz - 10khz
hi tom: 3khz (vintage) - 10khz (metallica)
mid tom: same
low tom: same
if you are working with drum mic's and a real kit, watch the 800hz - 4khz area, this can make your drums sound cheap if you dont cut. depends on your mic's and mic pre's.