from my point of view, here in London, the best to work is:
-a flat in a building of many appartments: more appartments means the movement neighbours see is spread between all appartments. nobody will think the punters come to you.
-NO CCTV. Many people think is not a problem. I was living 8 months in a studio with a camera looking at my door. It is very uncomfortable.
-A flat with ENTRY PHONE. In London many houses don't have this. If it doesn't have an entry phone, don't take it. You don't want to come out to open front door.
-a flat WITHOUT neighbour in front of your door. better a flat every floor.
Control the amount of clients. It is good to do 5 a day, ok, but if you are happy with 2/3 the better. If you have much movement people can be suspicious.