How can we apply these to our work and how we sell ourselves?

I like the bit about data reassurance (consensus), especially. I think that could be particularly strong when applied to UX designs. Interaction hinting, perhaps?

Also, leave all of our clients with a mint.

I'm going to frame this from inside the agency, rather than how we sell our product to companies directly.

Scarcity - We already have this down pat.

Authority - I think this is where youth counts against us where we lack the hierarchical authority in meetings to have our voices heard. This might be something that can be fixed through consistent, wowing work (and some top-down love).

Consistency - We need to get that process / deliverable document finalized. This will define the consistent expectations for us.

Liking - Requires similarities (look and smell like something familiar). Celebrate collective wins. Cooperate wherever possible.

Consensus - Goes hand in hand (for me) w/ consistency.