Unless you intend to spend days watching your scanner chug away at your huge stack of old photos and you want to fill up your entire hard drive, consider paring things down a bit. That old, yellowing shot of your great-great-step-grandfather golfing is a memory, to be sure, but is it a memory you really need to preserve on your PC?
Skip any photos that are damaged beyond repair. Time can leave its mark on photos, and not everything in those old albums may be salvageable. If you can still find the original negatives of your photos, use them instead of prints because they don't tend to fade and damage as quickly.
Don't try to fix your photos before you scan them; attempts to scrub them clean will only make the damage worse. Just wipe off the dust with a soft brush. You can clean up all the scratches and other blemishes in a photo editing program. Don't cut your photos, either. You can crop them digitally once they're scanned.