Right, all you need to do is decide what size (ratio) you will print them at, and then crop them accordingly. If you want to print 8x10 then crop as an 8x10 (or 4x5 ratio I'm not sure what wpg calls it).
So if I have cropped them with say 8x10 what will it look like if they print them in 4x6 and vice versa?? Sorry for SOOOO many questions...lol Just trying to get it through my head
KMH gave a pretty understandable image back there. I would go back and study it if you still have questions.
That being said, if you have a 4x6 (which is a 2x3 ratio which means that one side of the image is 2 units long for every 3 units of the other examples of these sizes of images being, 6x9, 8x12, 16x24) and an 8x10 (basically 4 units long by 5 on the other, examples being, 4x5 8x10, 16x20). Ok, now if you have a 4x6 and were trying to fit it on to an 8x10 image, the 4x6 would convert to being an 8x12, you then have to crop 2 inches off of the long side to make it an 8x10.
In other words, decide the images you want to print and crop them when you need to print them. What I typically do is leave all of my images in 2x3 (or 4x6 same thing) and then when I have people order them I crop them to whatever size they want.
It is pointless, in my opinion to crop all of them to all the sizes, why bother with it, just leave them at one size and crop when necessary.