How to Gain a Class Skill?

[Krell44]

I am hoping there is a magic item or something similar that allows a character to make a skill a Class skill.

I am in need of being a bit more...Diplomatic.

[Matthew Downie]

There are items that give you a bonus. Is there any reason it has to be made into a Class skill? Wouldn't any +3 be just as good?

[SlimGauge]

Traits are your best bet. The feat "Additional Traits" can be used if you're already past character creation, provided you still have the correct trait slot available.

EDIT:
If you don't already have a faith trait, Ease of Faith might work for you.
If you don't already have a social trait, Destined Diplomat might work for you.
Etc.

[Matthew Downie]

Page where people try to combine every possible source of Diplomacy bonus in case they need to pass a DC200 skill check.

[Krell44]

Matthew Downie wrote:

There are items that give you a bonus. Is there any reason it has to be made into a Class skill? Wouldn't any +3 be just as good?

Well, making it a Class Skill gives the +3 bonus, and then any additional items will give additional bonus. I'm not looking for the ultimate Diplomat but any reasonable way to increase the skill will be considered.

[Moonclanger]

The Cosmopolitan feat provides two additional class skills.

[Coidzor]

There are a couple of spells that let you treat yourself as trained in a skill and a number of buffs that give Insight bonuses to all kinds of skills. Bestow Insight, for instance. As a bonus, it lets you roll twice and take the better result if you need to pass a Diplomacy roll. On the other hand, with a sufficiently high CL, True Skill becomes the superior choice for an Insight bonus.

Similarly, Embrace Destiny, if you have a bloated CL or are able to anticipate when you'll need to make the check and only need a brief window of time but can choose your window of time in which to make the check, can let you burn spell slots in order to guarantee a good die roll.

Visualization of the Mind allows you to either A. give yourself an untyped +5 to Charisma checks and Charisma-skills or B. give yourself full ranks in Diplomacy but only for one minute.

Bit of Luck can be used to give yourself a potentially significant Luck bonus on a few specific skill checks.