can anyone here point me to a site with a decent care "guide" for amps? Both solid state and tube.

There must be stuff online... my own advice -- not sure what you have tho -- keep them clean, don't leave them in trunk of car, wet basement, attic, etc. get a cover for them, if it has original speaker and you are going to crank it all the time, put in a newer compatible speaker, save the original. Prob get better sound anyway. Old tube amps -- have a pro go over it. Old electrolytics should be replaced, weak/microphonic preamp tubes also. Check reverb tank to see that both springs are still hanging on. Make sure it has a grounded cord, since amps up thru what... 1967 or so (?) often did not. Even if grounded a/c cord is frayed, has ground prong cut off, etc. replace it.