Discounts on brand new cars

I am planning to buy my first brand new car, can you share anong negotiation techniques ang normally effective?

In my case eto ung finalist sa choices ko:
Fiesta 1.5L
Accent 1.6L (Dsl)
Elantra 1.6L
Altis 1.6E

My budget is a bit tight kaya major deciding factor for me is price.
I'm interested to know especially, gano kalaki or ilang percent from the list price normally ang nadidiscount pa.
I really like to get the Elantra or Accent diesel, kaso medyo lampas sa budget. If I can have an attractive discount malamang madadalian ako sa decision ko.

Any other sulit tips is welcome!