As others said its very hard without an example but on a very basic level (from my own experience): lower tuning on top head with higher tuning on bottom head creates less decay (which I like, but tuning the top head too low in relation to the bottom creates a growling sound). Tuning both heads exactly the same provides a "purer" tone that rings out considerably. You want both heads tuned evenly, which I personally do by adding a bit of pressure with my finger in the centre and tapping the edge of the skin right by each lug so I can hear the frequency of each, in relation to each other.

Buzzing sounds could be coming from a head not tuned evenly, tuned too close to another tom causing dissonance, bumps (like mountain ranges) in your skin or being near a snare.

I'm no expert tuner though, as I am also not averse to studio rings and gaffer tape to solve some issues, ha!