There is nothing universal on that path. Simply try to make a research, read as many reviews as you can. You can also contact several companies to see portfolios and to know the real prices for your final goal. I used to hire this amazing ico marketing team and have absolutely no regrets about the cooperation. I recommend to contact them with your task, they can develop any kind of business idea.
Use a wide variety of channels - I think the best thing to do is use a Wie variety of free ways to market. Use all social medias, don't just focus on Facebook, but LinkedIn, Twitter, reddit etc. Also I find that using Steemit is a great way as well, create blogs and spread them to reach more people. This can be done cheaply and effectively, just make sure that if you start a campaign that you carry it on.
Bounties and airdrops - these are the two main ways that ICOs market by offering their token as a payment for tasks. These tasks can be following pages, writing blogs, video creation, translations. Its a great way to create a community without having to throw a large sum of money into marketing
