Ah the Face, on the surface it might seem like such a simple role. However I find that it can be one of the most complex ones. I've been in games that were the Face of the group never really spoke in game. You could go for 20 minutes with them just sitting there and listening unless prompted to offer input. The team met the Johnson, they rolled negotiation and they were done until the shooting starts.
As a Face, you need to be proactive, you need to be creative, you need to be active. A Face is not a passive waiting for things to happen role.
In my opinion, a Face needs more than just the social dice pool. A Face needs a lot of contacts. Next to the Matrix person and the Face are the two main sources of Legwork for a team. The decker can hit the Matrix and search for info sure, but the Face knows a guy, who knows a guy who knows a guy. You should have contacts in various social circles. Corporate, Street, Local Government, Law Enforcement, City Services, Organized Crime, the list goes on and on. Your finger is on the pulse of the world.
A Face should be a social chameleon, you should have a lot of different outfits. Sure the trusty Armor Jacket is a big beefy 12 armor in 5th edition, but it really sort of stands out at a formal dining situation. Your Lined Coat might be the definition of black trechcoat cool but if you're trying to pass yourself off as a wageslave it might not pass the muster.
Having several fake SINs also helps. OK so you're tooling around Seattle use your Area Knowledge to figure out which corporation has the most presence in the area. Use a SIN for that Corp. KE stopping the car, ha got a R5 fake License that shows you're a KE officer from another city. "C'mon guys, we're on the same team here."
In closing the Face should be a sort of in-your-face making sure they're always working an angle to help the team out. If not then you're basically a pretty street ganger that can string a few words together.