I agree with the above statement. For most overdrive pedals, however, there are some "standard" settings that I find work well for most amps.
First being the classic SRV clean boost technique of diming the level and keeping the gain to a minimum. Set your EQ to taste depending if you are playing a dark or bright sounding guitar. I typically like the tone between 10 o'clock and 1 o'clock depending...
Second is if you are using a super clean sound already. I usually set the gain to at least noon, sometimes 3 o'clock and then bring the volume of the pedal to just above unity volume when you kick the pedal in. A lot of times it's between 10 o'clock to noon on the volume dial. This works great for adding basically a second channel to a nice sounding clean tone. I like doing this with a Fulldrive 2 and a clean Super Reverb.
'67 and '74 Fender Twin Reverbs, '74 Marshall 1987 lead mkII, Metro Superlead 100. Pedals from TC Electronic, Ibanez, Dunlop, BK Butler, Electro-Harmonix, Fulltone, Maestro/Gibson, Loopmaster switching, VoodooLab, Boss. Gibson and Fender guitars, Dimarzio pickups.