At Pocket Gamer Connects Helsinki 2016, Eric Seufert, a partner at Heracles, gave a talk on how to run a UA campaign with only a barebones staff.
He said that the tactical difference between companies with a lot of UA resources and one without is that the less money you can spend, the less data you can gather, and the less certainty you'll have with your UA campaigns.
To combat this, Seufert said devs need to "focus on incremental growth, gathering data, building confidence and increasing spend in bits".
He added that developers need to focus on "slim yields at conservative LTV estimates" so that you can bring in as many players as possible that will actually monetise.
You can see all our videos from Pocket Gamer Connects Helsinki 2016 in this YouTube playlist.