timing problems

ok i tried to advance my timing, but all i noticed was the idle either speed up or slowed down, i didnt really know what to listen for, so i tried to put it back in the middle where it was, but now my idle goes up and down and up and down, like so many hondas i know do. so 2 questions, how do you advance timing properly and what to listen for, and 2 how do i check my timing with a timing light. thanks alot i really need help fast.

you probably didnt reset your computer when you got done messing with the timing,
drive around for a good hour,wait,drive again the next day,
it'll clear up,
I just got done putting my oil catch tank on & didn't reset the computer,
it idle'd up & down,up & down
it soon cleared out & quit,-slowly
but to set your timing,--I have a good mechanic I know that can set his/mine to advanced/retard by the sound,,,but I have no clue what to look for,
try your best to set it dead in the middle,
(thats if your messing w/the d series distributor)
then work your way w/very little-I mean little- notches toward the firewall,
(towards the firewall-advanced,,,,,,towards the front of the car-retard)
maybe 2 mm/3,would probably be fine,(depending on your setup)
its better to be safe then sorry,(remember to mark the distributor on to the metal thing(that sticks up beside the distributor)when you have it in the middle,
so you'll know where to go back,
but you'll be fine,
I just got my adjustable cam gear & the notches on it are seperated by mm,
hope I could help,good luck

thanks for the really good information. one more thing, i have a d series motor, but how can i check to see if my belt slipped a tooth or not, im starting to think it has judging by some of the noises my engine has been making, and the timing belt seems kind of loose, almost like i could slide it off the cam gear if i wanted to. is this normal? but id really like to know if its straight or not.