I've had a few two girl's over the years.
My advice would be to make sure you have seen at least one of the girls before on her own.
That way you know the kind of things she is up for, and that you like her.
The one you have seen before will be able to describe what they will get up to,
and you will be able to tell whether she genuinely sounds like she enjoys her self doing it.
No point paying double the fee, to be dissapointed.
I can reccommmend a 2 girl BJ, one on your cock t'other licking your balls......bliss
then doing one from behind while the other licks your balls, or gently cup's them....double bliss
make sure you go for the porn star finish, get them kneeling together, and give them a shared facial......
Fuck it I'm off for a two girl !