Accented hair Kennedy's are not easy to spot. But maybe this link will help:
L I N KFirst of all, it must be a 1964 proof Kennedy 1/2 dollar. No regular issue Kennedys have the accented hair.
Next, look at the reverse and see if the attributes are there (i.e. "FG" with no serif on the G, broken rays). If they aren't, then it isn't an accented hair.
If the attributes ARE on the reverse, THEN you should look at the obverse for the wishbone-shaped area which isn't on the non-Accented Hair coins.
This is because there are some non-accented hair Kennedy obverses paired with the accented hair reverse. Unfortunately, they do not command a premium, AFAIK.