Well, with you not really knowing the city and it’s relative pulse, I’d tailor the opener set to fit what the headliner is known for. If he’s a respected DJ, as you say, then he would have a particular sound, so, I would do a set that lightly treads that sound while still incorporating your own personal style – that way, even though you’d be opening, you’d be less forgettable.
There was also a decent DDJT article that expanded on doing opener sets – 10 Secrets to Opening For Big Name DJs so, I’d say check that out too for some surefire pointers.
Best of luck though, trust your gut more than anything and have fun 🙂