It's obvious that John F. Kennedy is a style icon. Everybody is trying to get that classic swagger. If you wan't to achieve the look you need to have a few essential items. I've compiled a list of what you need in order to look like you've been walking through the sand in Massachusetts.
The List:
A lighter sweater for that beach weather.
The oxford is key. Go untucked, but make sure it's not hanging down to your knees. The fit is crucial.
Go with a 7" short. Khaki.
Go with a braided belt.
Ray Ban Wayfarers are obtainable and they will never go out of style. If you have lighter hair get tortoise shell, if you have dark hair, get black.
Get some loafers. Boat shoes work too, but you most likely don't sail.