If you aren't already, set up your scanner to scan directly into Adobe Photoshop (or Photodeluxe) These graphics programs are the best way to 'touch up' your scans to make them look their best, and scanning directly into them takes no more time. I always open my Adobe and do a "Import Twain_32" to initiate a scan. I know, it sounds wierd but that's the terminology they use.

In particular, experiment with the 'sharpen' function and the 'adjust levels' function. Amazing what they can do to a so-so scan!