Did our first urban sesh of the season today. Turned out fantastic and we got some sick shots!
Biggest thing I'd say is to be comfortable hitting rails with higher speeds. We were towing in to day (the inrun was uphill) at about 21 mph behind a 4wheeler on a wakeboard rope. Urban rails tend to be slightly stickier so the extra speed combined with some wax if you got it will make it slide much smoother. Also be good at landing on your skis when you bail off of a rail and be prepared to ding up your bases pretty good.
Other than that, just make sure to have a fun time and hit it!