Finger shapes and how they should effect ring shopping.

We were not all created equal! As there are many body shapes, there are also many finger shapes. You should know what kind of fingers you have and styles of rings that best suite you.
I'm going to list the shapes I know well, sorry but I haven't come up with flattering names for the them!

Skeleton fingers - that's when the knuckle is wider than the area of the finger where the ring sits, this means that the ring will always spin. This can be very irritating in a signet or traditional engagement style ring, because the heavy top slips down and bothers the neighbouring fingers.
Try to pick ring styles that have a continuous pattern, if there is no bottom your ring is never upside down. Try a soft square or stirrup shaped ring, these ring shapes hold onto the finger better and feel less irritating between the fingers. You should wear wide rings, they will look great on you! Do not get a ring that is comfort fit or that tapers from the front to the back.

Sausage fingers - that's when the fingers look tight and tubular, sometimes they bulge out on either side of the knuckles. Its hard to fit rings to these fingers, they always look like they were stuffed on!
Try a narrower band, less than 5mm wide, and thin - 1.5mm thick. Comfort fit bands look less tight, but must be thicker, which may not be comfortable if the fingers have no space between them. If the fingers are close together than get a low dome ring, that way you have no edges to irritate the neighbouring fingers.

Swelling sausages - you do not have ring fingers. I should not wear spandex. We must both deal with these things. IF you feel you must get a ring, or your future spouse insists you have one then buy 3 silver ones first, all within a 1/2 size of what the jeweller says your finger size is. Try them each for a week. Then retry the first one. The correct size will feel too loose on a cold day and not turn your finger blue after exercise. Best bets are soft squares and comfort fit bands, try a tapered band too. Assume that you will wear this ring only for special occasions.

Carrot fingers - that's when the finger tapers towards the knuckle, most people's pinkie fingers are carrots. You can wear any style, but you must wear it tighter then you want because otherwise it may slip off.

Ring fingers - you won the lottery, you have the perfect fingers for wearing rings! Nicely tapered, the knuckles dont stick out, the the skin is firm but not tight so it sticks slightly to the metal, you dont swell....now just dont age!