Photoshop :: Adding 'texture' To A Replaced Face

I'm using PS CS3,

I have to take old black and white photos and replace the old faces with those of living people. The photos were scanned out of various photo books, and some of them were quite old. I used de-screening when I scanned them in, but there is still a 'texture' to the original photo and it doesn't look right when I put a nice, clear face off a digital camera shot to replace the original face.

I can buy a DVD tutorial from PixelPops to show me how this is done, but is there a simple way to do this so I don't have to spend the money? Yes, I can do a google search, but I don't even know what term to use for this particular process. I thought it might involve the healing or cloning tools,