Start by scanning the images at least 2 times the actual size in the document and at 300 dpi. Next duplicate and save the originals to a safe place then work on only the duplicates. Do all of your image placements and design work, including recolor, touchup, editing etc. After the final document design has been approved for print, resize the images to 100% @ 300 dpi and in the image mode they are to print in. Collect for output, print a couple of proofs and deliver the files and one proof to your printer.
But always verify your printer's specifications prior to doing the final pre-press work. If they get a file that doesn't work in thier printing system, they'll either charge you to fix it or you will have to fix it.
I hope this helped. Good luck.
Greg B.
