Instead of using a standard bandana and tying it around your doggos neck, try this one instead! It simply slides over the existing collar. This eliminates nearly all the wrinkling that comes with a standard bandana, you can twist it around to the front or the back for photo opportunities, and it lays nicely when on. 
 
XS-Daschunds, Yorkies, Chihuahuas, etc...
S-Boston Terrier,  Spaniels, Schnauzers, etc....
M-Bulldogs, Australian Shepherds, Basset Hounds, etc....
L-German Shepherds, Rottweilers, etc...
XL-Great Danes, Cane Corsos, Bull Mastiffs