Inquisition perks

Deft hands is a perk that you purchase from Leliana at the war table once you have a perk point available to spend. If you have a perk point, using the war table should automatically open the perk interface. Deft Hands will require you to have 4 perks already used with the advisor. But finding agents will count towards this requirement, so you don't have to use your perk points to buy other perks if you don't want to, you can go out and recruit agents.

But as Tinolyn said, you need to earn influence to reach new inquisition levels. You get one point at each new level, and the max level is 20. So you can't earn all inquisition perks, so think about how you will spend them. Completing quests, turning in requisitions or buying treaties from the Skyhold vendor (not available right away, requires war table op) are the ways to earn influence.