Hi,
Reviews and verified photos are the only way you can pick out an escort. That doesn't mean that your encounter will be a good one. It all depends what your into, of you read all the reviews of the lady you will get an idea of the type of service you will get.
I would stay away from escorts who offer all of the services possible as chances are they don't and only put that down to get punters in the door. Escorts who have reviewers that have been more than once or twice is also a good sign.
If you stress about meeting an escort you may not enjoy your encounter, so relax enjoy and learn by your experiences. When I started punting I would never had dreamed of the situation I have ended up in, it's amazing. So you never know where you'll end up with punting. See as many of the good ladies as possible and enjoy it, if it doesn't work out, move on and pick another.