how do i befriend another dynasty?

[SpiritRetro]

title.

i wanna know how i can improve another dynasties opinion of me, become friendly with them and eventually ally with them

[Vote Quimby]

There are few options.
Thumbs up their buildings(i forgot how action is called, looks like finger up).
Vote for them in political offices(not really recommended).
Use consumable items, such as Wine, Poems, Bucket of Flowers, etc.
Key to the City political action give a hell alot of rep.

[Skumboni]

Easiest way to get alliance is at the start of a game. Offer to ally with each of the other dynasties for 500g, they will take the offer giving you some nice gold. Later you can break the alliances one by one when you are ready to eliminate them, Another advantage to this is that you do not get robbed as all the thieves are allies.