If it's naturally frizzy then I would wash it, and blow dry it straight. When it's very straight then you can use straightners or curlers to put some loose waves in it.
If you try and do it wet, the waves might look a bit frizzy when they dry.
OR,
There are loads of great products now like Frizz Ease especially for stuff like this. I'd recommend a slightly cheaper one - I think it's by Loreal it's in a bright pink bottle, there's one for straight hair and one for curly hair.
If it is a permanent look she is looking for then ask your hairdresser to do a bodywave on her.
I just recently had one of these donw myself and it turned my frizzy curls into structured loose curls.
If it is a temporary fix , then blow dry the hair straight and use tongs and a felxible hairspray , depending on her hair type they may even last for a few days
Wit short hair it shld b big waves but if u get curls make sure that it is loose not tight curls cos it would be very very wild lookin and i dont think u want to look like that.. From woman to woman u got a man u need too look gud for him not bad looking..