First you need a website. I'm using Weebly, because it is awesome, free, and self-explanatory/easy! Sign up to all of these Sites and post about them on your website. Why is this effective? You get paid when your visitors sign up to these sites for free!
Ibotta - $2-$5 per referral that uses this awesome app once. Use VYPW as your sign-up code to get the sign-up bonus. To get the $5 commissions, you have to email the Ibotta developers.
Cash.me - Earn $5 per referral who downloads this app and signs up with your code. Use HWKWQCP as your code for YOUR $5 signup bonus!
BraveApps - $1 per referral.