My experience in other places on the mainland of China is as follows for your reference:
1) take a taxi at the right time, say around 9:30 PM, a bit earlier
2) chat with the driver and test the waters
3) if the drive is a newcomer, find a new taxi as soon as possible, repeat 2)
4) if the drive is an experienced guide, tell him what you really want to do this evening, including your requirement and budget
5) give him a tip if he can do the job and right after the job is well done
6) you'll, in most cases, be taken to where you look for
Of course, this little plan needs talking in mandarin, as all taxi drivers in Shanghai, even in the whole China, don't have any idea of English. In my view, a little bit Chinese is more than enough. Or, you may try to show the following characters to the driver:
1) 找漂亮妹妹 (looking for a pretty girl)
2) 价格合理 (reasonable price, say, below RMB 500)
3) 安全 (safe)
Good luck.