From a legal standpoint would these be useful precautions to take:

1) Bring a camera and ask for nude photos.

So I was watching "manswers" on TV awhile back and the subject was, "how do I know that the prostitute isn't LE?"  The best recommendation they gave was that you should ask if she does naked modeling.  The idea being that the activity isn't illegal but would require a payment and a girl working with LE would be unlikely to want to have naked pictures taken of her.  Therefore, in court, you can make the, "I was there to take naked photos but we liked each other and one thing led to another argument" and actually back it up with some evidence.

I'm also concerned because, after reading a lot here and other places, it seems that some providers don't like that question (provider feedback would be appreciated).  It seems to me that the question should be something a provider would want to hear because you're essentially asking, "hey are you willing to create some reasonable doubt with me?"

2) Try to disguise the donation as a gift.  

For example, put the donation in a B-day / christmas / valentines day card.  Again, the idea being to create some reasonable doubt by being able to say I just wanted to celebrate the event and one thing led to another.

Provider feedback would be awesome here too. Would this sort of thing creep you out?