I think the best form of marketing is word of mouth, if there is a good project then they don't need to shout it from the rooftops, people will realize the potential and they'll tell others about it, soon it will spiral and the project will be very popular.
really, word of mouth is the right way to market the project because people will be more confident than the words of other people who have experienced or from community leaders.
But marketing it on Facebook, Google or Bounty in my opinion is also very important because it will be more value if a project has a good marketing technique