I am a newbie obviously.  Is it customary to tip beyond the standard donation when the service is exactly as described up front, nothing more or less?  I am not cheap and would gladly tip but I don't know what is the standard practice. Thanks.

and that the best tip is to come back and see the gal again.

Now, for if for some reason, you feel the gal went above and beyond the call of duty, then tipping is a very sincere way to show your appreciation, and I do so myself.

As for DIY, if you think the massage was worthy of an extra tip, then go ahead and award her 25% or so for that.  If she throws in some Oscar worthy special effects, maybe even a little more.

As a sensual massage provider, (non DIY, btw!!) have often returned tips if I knew there was one included while it was being handed to me.    I think my fee is fair and I prefer clients save up for their next visit.  I realize people are not made of money and I'm certainly appreciative of the fee only.

I don't think you should feel pressured to tip.  If a provider has a fairly low rate, maybe it is because she is expecting a tip, in which case tip according to your satisfaction level.

Thank you both very much.  Your comments were helpful.

that repeat business is much preferred over a tip.

Unless YOU feel that the service was "above and beyond" what you expected.
Or if the lady's flat rate is below what you WOULD have paid.