There are two factors that I personally insist upon in my own scanning:
1. Don't let the scanning software do ANYTHING! No rotating, no resizing, no descreening, no sharpening, no NOTHING! Scanners are at their best when they capture an image - EVERYthing else can be and should be done better in post-processing software, be it Photoshop, Elements, or Corel or whatever. Letting your scanner make decisions for you will guarantee a lesser-quality scan than you can do yourself. It may take a little practice, but believe me you can do better than the "averages" that are used by the scanning software.
2. Never scan in .jpg! JPEG is a lossy compression format which means that your scanner is going to decide to throw some pixels away when it saves the file in that format. I'll repeat that: When you save in JPEG, you're not getting all the information that your scanner took in. And, even worse, if you RE-save in JPEG later, the compression throws MORE pixels away in its attempt to compress the file even further. JPEG should be the FINAL conversion you make after scanning, straightening, cleaning, etc. Scan in TIFF, PNG, PSD or whatever, but not JPEG and not GIF. If you're sending your scans to someone else to be edited, it really is better to send them larger files in TIFF format than it is to convert to JPEG, let them edit the files and then have them convert them to JPEG again. Honest.
If you have Photoshop or PS Elements 3.0 or later, you have access to adjustment layers and they can allow you to do non-destructive editing and color correcting - which is great. If anyone wants to discuss how to use them, I'll be happy to explain.
Peace, Jim (|:{>