Once you've reached Episode 2, you can automate your Strains!
Automation requires a certain Crew Card at a specific level and a certain amount of Cash. This varies Episode to Episode. You'll see some rotating arrows beside a Crew Member. When it turns from grey to blue you'll know you've met the requirements to automate that Strain. You can always tap on the grey arrows to see what's required to automate a specific Strain.
Once automated, Strains will make Cash at the same rate as if you were playing!