It's often best to match the frame colour roughly to the
background of the picture, so that the viewer's eye isn't drawn away from the principal subject.
For instance (to use your red dress example) I'd consider framing this picture
http://inetnewsreporter.com/wp-content/uploads/2014/07/Lady-In-Red1.jpg
with a shade of grey just a little darker than that of the picture's background.
Here a sparkling white frame might be appropriate:
http://stockfresh.com/files/a/ariwasabi/m/55/1646602_stock-photo-beautiful-woman-happy-screaming-in-red-dress.jpg
Wherever possible, the environment into which the framed photo will be placed should also be taken into account. Bold-coloured frames can look great in large 'modernistic' rooms but totally out of place in small 'chintzy cottage' style rooms. (Natural wood frames are probably best in such rooms).