You could get together in a big group and all say the same things in unison. Maybe even hold some signs saying those things
See e.g. throwing oil on famous paintings, or everything re Palestine in the past couple of years.
Protesting effectively is a skill which the present generation lacks. They don't even realize it's a skill issue. "Surely if we just care harder somebody will do something..!", they think, over and over. Doesn't make it so.
I will also tell the friends I made/lived with in NDDL that our action had no impact and that the airport is being built (given that a couple of them bought a house where the airport was supposed to be, they might not all believe me).