Pathfinder Diplomancer feats

[Renen]

What are the best feats for pathfinder diplomancer? (Using Pathfinder books only)

[Blyte]

Human with the alternate racial feature Focused Study that gives multiple skill focuses throughout the life of the character, and perhaps start with skill focus diplomacy, and eventually skill focus bluff and sense motive.

The feat Cosmopolitan will help you get skills on your class list as well as bonus languages.

[SowZ]

Diplomacy I can do.

Silver Tongued Human for +2, Skill Focus for +6, Persuasive for +4, Rhetorical Flourish for +4 with a successful bluff check, Negotiator for +4, Voice of the Sybil for +3, Patient Optimist for +2 vs. Unfriendly or worse and a free reroll on failure, Alluring (Trait) for +2 vs. attracted and other benefits, World Traveller or Ease of Faith (Traits) for +1 and counts as class skill, Chivalrous (Trait) for +1, Ambassador (Trait) for +2, Charming (Trait) +1 vs. opposite gender for diplomacy and save DCs, 150 GP of Jewelry +1, Ancient Splendor for +2 or +4 vs. dwarves, (Weapon or Armor enhancer,) Book of Letters, (Item, +2 when dealing with city officials.)

I didn't include things that don't work for non-humans.