best way for a passenger to ride a sportbike?

[AquaPython]

i have virtually no experience personally riding on the back of a sportbike, so for years i have gone by what others suggested to me for my passengers.

mainly,

a) dont hold onto me, rather reach around me and support yourself on the tank.
b) make sure not to head butt me from the back
c) lean with me , etc...

my GF seems to always complain that she has hurting hands / wrists because of the pressures applied when i brake. even when i take a long time to take a slow easy braking ride. because of this she doesnt want to ride much and doesnt enjoy it, and when she does, she cant handle distance longer than say, 10 miles.
what is she doing wrong? or what can she do?