I recently had my first experience with a provider.  She was an independent.  Great service.  At the end of the session I gave her a 15% gratuity.  Is this acceptable?  Is it customary to tip?  Would not tipping a provider be like not tipping a waiter?

Politically expedient? Absolutely!

   A waiter is often paid minimum wage by the house and his gravy is the tip. An independent provider is commonly taking $$$ donations for her hour of service. Naturally if she does an exceptional job and you wish the same attention to detail on your next appointment a tip would tend to insure this.

I have never had high performers ask for tips, typically the lousy ones do that.

Good point, which is exactly why I never give a tip if it's solicitated. The deserving ones never ask for a tip.

I'm sorry, but the "Good" providers are $$$ / $$$.5 or even $$$$ per hour.  That's EXACTLY what I am paying for.  Call me cheap, but I do not tip.  I bring little gifts (flowers, candy, wine/champange, etc) and that is my token of appreciation.  Do the math, they can easily make up for their costs of hotel, etc (which - sometimes I pay for) with 2 or 3 clients per day.  And still make a little spending money.  
Just my .02 cents - Literally !!!

I don't think you are being cheap. The cost for indies in our area is going through the roof. Why ? Good question,the inflation rate is actually low despite a rise in gasoline and home heating fuel. Six months ago I saw a lady who is top of the line for 300 an hr, 600 for two. Today she could easily get 500 hr in our overpriced area. I honestly don't think she'd do that though, more like 350. Unfortunately she is not available anymore Some indies, such as my ATF have held costs down in appreciation for long time clients. They are pretty rare though these days.

Anyway ,I'm like you, a small gift on occassion and never a tip for an independent.I do have a weakness when it comes to agency ladies who go the extra mile,even if they are not a true gfe in my book..I'll always leave extra for them.

Do you tip the provider when the House already charges you 2oo for FS? Is it already included in the donation?

Other AMP's charge 6o for the massage then (YMMV)if you want extras. Adding extras will be about the same price as FS (above).