you don't have to write a novel. Be honest but not mean, to the point, I believe that certain acronyms must be discussed in order for the lady to get the score. (if it happen, make sure you post them).

Reviews should give hobbyists enough info to help them decide whether they want to see the provider.  They don't need to read like a romance novel.  "Just the facts" is fine.  But please make it easy to read--use of proper punctuation including paragraph breaks is greatly appreciated!

Never include any details that could possibly be unsafe for anyone, e.g. which could be used to identify the provider or her location, or in general give personal information about the provider or anyone else.  

Also IMO it's possible to write a helpful review without embarrassing the provider.  It shouldn't have to be said, but sometimes it seems to me that reviewers forget that providers are people, and they have feelings.  Be honest, but try to be kind also.

so don't put down yourself because you have an honest trade.   What you wrote above is more cogent than a lot of the drivel that ends up on here.

 
Use discretion on the details.   Ask yourself:   Do the other hobbyists need to know this information?
If the answer is yes, then include it.   On the other hand, if the info is not that important and could disrupt your relationship with the gal and/or make you come off as a jerk, then don't.    Obviously there is a lot of gray area there.   It's what makes life interesting.

A little addition

Just to add to all the great points, sometimes use a bit of discretion. Some acts are reserved for you alone or a chosen if the provide likes you. Some providers will go raw if you prefer but only if they're comfortable with you but don't want others to know. It's a grey area as others will want to know if the person they're seeing goes raw and will avoid them. It's up to you.

I've found that writing reviews is hard and it is a delicate balance.  Writing a honest review in a tasteful manner is the best approach.  I would suggest re-reading your review a couple of times and editing it before you post.  The goal is to express the moment in a way that will allow other mongers to decide whether to see or not see the provider based off of your review.  Also, keep in mind the women you are writing about have feelings and will read your review.  

writing a good review is walking a fine line between enough detail and too much detail. poster above was partially correct, it is difficult to write a good review without embarrassing the lady.  However. in my (limited) experience, some ladies are not embarrassed at all by graphic detail. This is advertising for them after all.  
You take a chance of spoiling the mood, but you can ask her before you leave how she feels about reviews and if there is anything she doesn't want written.
One good piece of advice that I rarely follow is to wait to write the review a few days afterward so that the emotion of the session has a chance to dissipate.  
just my 2 cents