I've been working on scanning personal and family photos, slides and negatives for a while now. Slides and prints are being done first. Negatives will be last. I've been using a V600 and a FastFoto FF640.
Some things I've noticed that may or may not help:
My V600 seems to be properly set for focus on images in the holders. Prints tend to be a little less sharp than slides (as long as they were properly focused when taken). I'll see how the negatives look sometime later down the road.
I seem to get more accurate and consistent color from slide scans than prints on the V600.
If you have a large number of prints, especially if they have identifying info on the backside, the FastFoto scanner is a huge timesaver. It can scan front and back on the same pass and saves the files as "a" and "b". If you also have documents to be scanned it can do those as well, and save a stack on papers into one pdf in one easy step instead of individual pdfs that have to be combined. Again it can scan front and back on the same scan pass. My prints are sharper when scanned by the FastFoto. However, super glossy prints from the '90s onward seem to have a slick plastic film on the paper that can slip when feeding through the scanner and cause distortion issues. I have to do those images on the flatbed.
edit - I tend to not use automatic color correction on either scanner. Might just be my copies, but the corrections are all over the map. Sometimes good, sometimes not-so-good, sometimes clown world. Plus, slides from the '50s and '60s seem to hold their color well.