I would never ask for a discount, as most seem to take it as a personal insult. It's almost as bad as asking for bareback or hardsports. I'm sure we've all read the standard FAQ that says - Please do not insult me be asking for...
I just think practicality. Asking outright will often just sour things before getting off the mark, but skilful negotiating is another thing. I think that's maybe where we can usefully share ideas.
For instance, girls sometimes have a special offer. If the punter wants that rate when it doesn't apply, he can always insert (in convivial chat while you're warmed her up), "I was just about to book you for tomorrow afternoon - the only time I have free - but now I notice your offer doesn't apply then. Drat! I have a rule about how much I spend on my 'hobby' and don't let myself go over that. Oh well . . ."
What does this tell her?
1. You are not a timewaster - you are about to book if the price is right
2. You are not hassling her for a discount - in fact you respect her pricing structure
3. You really like her
4. You are not a cheapskate (notice I 'have a rule' not 'I don't think you're worth more than what I'm prepared to pay')
5. She has a definite offer on time and price if it happens to fit her diary and doesn't compromise her.
6. You're not a textspeak moron
I'll usually throw in nice images casually in the email - I have good feedback - I always make someone welcome (if my place) with a nice glass of wine or something - my place is easy to get to and in a nice district - I particularly like (some daft wee thing from her profile interview like her taste in music.
I basically make it easy and pleasant to do business with me at my rate but - and this I think is very important - without her losing face.
In haggling, any haggler should know (as should any salesperson) that a mutually acceptable 'excuse' is needed to agree a discount. I happen to be in the area. Just this once. I would only do this for someone I trust - don't tell anyone else - we might as well, but don't expect that deal in the future. It doesn't matter. Any old shit. Just make it easy for her then let her offer you
the discount. This has worked so often for me and not just with prossies. I can't recall ever specifically asking for a discount - but I've secured them more times than I can count.