The one of the most effective thing in the Marketing of ICO - it is to attract good advisors with really great background. I think that investors more trust to people than to advertisement.
What is interesting, I've got an impression everyone is associating marketing only with ICO and pre-ICO activities, like, there is no life after ICO. Isn't the second part is also very important - how to market the existing project, to grow the price.
According to to data I have, most of the tokens actually lose capitalization after ICO. Isn't it because everything is concentrated on "sell it" thing?