The art of
Once you have a collection of sounds you may want to reuse them without them sounding the same.
There are many techniques that don’t require an awful lot of work to sculpt a drum to an individual track. One of the easiest improvements to a sound is to Tune your kick drums to your bass line. This can prevent clashing of sound and drastically improve a mix. If you have a long ringing 808 style kick you can toss a tuner such as guitar rig over the sound and watch what key the drum is tuned to. By simply pitching up or down you can tune it to the key of your bass line. simply throw a tuner (guitar rig for example) onto your kick track is a dirty fast way to get an idea of your kick or you can use a spectrum analyzer and look at where the harmonic frequencies are prominent. though I tend to just use my ears for this process.
Another great way to sculpt a pre made drum is by using bit crushing or distortion. Adding subtle to drastic hints of lo-fi to a pristine sample can really change the overall sound of a kit and create a drum sound totally new.
Don’t forget filtering and layering of premade sounds as well. And always keep an eye on your levels. When stacking premade drums it’s very easy to start clipping so turn it down a bit and you shall be fine. Adding harmonics to a sound can be a great way to alter a drum or instrument as well. adding Ring modulators and tuning the ring mod then resampling is a great way to enhance a sound. There are pleny of options and ways to do this. Everything from guitar plug ins and actual hardware fx pedals to Reaktor ensembles to simply getting creative with the EQ.
Also a spectrum analyzer can help you see trouble frequencies you might not be hearing such as increased bass tones below 40hz that are causing mixes to peak even though they sound quiet. Simply filter them out or use a sculpting EQ.
Sometimes simply routing sounds out of your computer and through something simple like a korg monotron or a aha pedal can change the sound just enough to make it feel new and fresh to you. Experiment and have fun with it.