OK, let's try this. I've been mongering for more than a decade, and even though I've seen mostly agency girls, Ive seen some independents too.

One of the main things I'll say, don't be afraid to leave honest and correct feedback. Don't fear the pressure of trying to make the session in a review any better than it actually was. With that said, grade fair and like she will also grade YOU as a monger. Provide helpful feedback. Obviously, when you see a low volume independent, it's much easier for them to link you to your handle, so there's inherent risk of your honest feedback met with disdain and BL. This is why I suggest getting some verification that doesn't expose your handle. Or using an alias.  

You might be tempted to make the feedback more favorable, because it will make your 'acceptance' easier and you will be able to get through the vetting process easier. However, long term I don't think it will  matter, and you end up misleading other mongers.

If you're a newbie, most of your info will come from reading reviews and scraping boards for info. So it makes sense that once you start being an advanced newbie, you also help the fellow brothers who are on their way.  

The impact of making reviews better than the experience tends to lead to oversaturation and reviews mattering less. It goes without saying you should not make the reviews score lower than your experience actually was. Don't be that guy who holds a grudge against the girl.  

It might be difficult in the beginning, but as you along, people will recognize you as a fair grader, and people will listen to what your reviews have to say.  

Good luck