Start by scanning them properly - with a black sheet behind to eradicate backside text and otehr stuff that shines through and allowing youer scanner to determine the whitepoint based on the document, not the scanner lid. The rest is beside the point - you always scan at higher resolution than you publish to have room for scaling, cropping and generally working. In fact one might need to work at even higher resolutions. If this goes to print, file sizes don't matter, if it's for online publishing, converting the publication to PDF and optimizing it accordingly or creating JPEGs will take care of matters. You really need to read up on that. As for procedures, you shouldn't expect a magic button. Generally one would duplicate the source a couple of times and belnd it back with blending modes like Add, Linear Dodge, Multiply and so on to intensify or tone down certain colors, then use further adjustments to recover contrast and further remove artifacts. Some of the stuff will however require painstaking cleanup with the clone brush and otehr techniques...
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