It's a good idea to have a be of a USP, but more importantly it's worth mentioning simple things like being British (or whatever nationality if you're something a bit more exotic!) or being busty or raven haired, men are quite simple really in what they fancy!
I think having a clear persona is helpful rathe than a USP - you can't be everything to everyone so don't try to be a sophisticated, elegant, cumguzzling porn queen at the same time! Really think abut what services you want to do, I learned when I started that doing something with a trusted lover isn't the same as with a client and be as honest as you can about your abilities/services - claiming to be the best ever at blowjobs might leave you unstuck if you get a 10incher wanting deepthroat! If you can do this then definitely say so though!
This might be unhelpful, but I found that it took a little while to work out what worked for me, and that has evolved over the years so don't feel you have to stick to everything you first decide on and you might find you get a certain sort of client and realise Ahh, this is what men like about me and play on that.
If you're nearish to Gatwick and happy to do outcalls its worth mentioning that heavily - Hotel outcalls can be fun and lucrative and I always feel super safe (I'm near Heathrow and the hotels are big and busy at all hours and no one cares who is coming and going)
As for personal possessions keep jewellery, anything easily picked up out the way, letters with your name on obviously and I personally have never had photos of friends/family around. Felt too weird clients seeing them.
Unless you're advertising a super smart fancy booking for plenty of money then don't bother with champagne, I have never offered alcohol or been asked for it - most want water or occasionally tea. Candles are nice but not essential. Good lighting is important, not to bright and not so dim you can't see what you're doing! And, and this might be a bit obvious, just keep the space clean and clutter free to retain the illusion!
Have masses of condoms in (some of the will get through more than you expect!) and some large and small sized ones, latex gloves (of you do anal play), lube, baby wipes and tissues.
Think about the bathroom, offer a shower, have large towels at had and I keep 'male' or fragrance free shower gel. They don't want to go home smelling of roses or other feminine scent!
Hope that helps a bit!