Digital BW, The Print

Hi All, 
I am particually interested in what might be the size of print and 
matt you might use? I know this is very subjective, but I want to 
mattt some prints for resell, the print size being, say 8x10. Should 
I make the matt a little larger for my signature and print name? How 
big should I make the matt. I use a Canon digital camera and of 
course the format does not match the 8x 10 format.Any suggestions?

Thanks,

Barry