I do Android apps, and tried lots of different advertising approaches. Admob has always been a central ad network to consider, then everything else. So first

I do Android apps, and tried lots of different advertising approaches. Admob has always been a central ad network to consider, then everything else. So first you want to decide if you want Admob to be your ad mediator or not. If a third-party one works acceptably with Admob, that's your best choice. Then you want to do the split. Admob has high fill rates and good numbers for most countries. The top competitors usually only have high fill rates for countries like the USA. Usually their numbers (click through rate, payment per click etc.) is less for those countries as well. I usually send most traffic to Admob and let a little dribble over to an Inmobi or AOL One (Millennial Media) or whatnot. Aside from spending $150 on a few things initially (A few months of a VPS, $25 for a Google Play developer account etc.), all the money I have spent on my apps - advertising, translating, icon art, VPS charges etc. - have come out of revenue. That was easier up until 2014, when people were getting their first Android phones, and their weren't a lot of apps and Android programmers out there. Now there are a lot of good apps, Android programmers etc., so getting traction on an app costs more and/or takes longer. I get e-mails all the time for some new ad network and ignore almost all of them. Admob towers over most of the other ad networks for people building standard Android apps with Android Studio. I use the major second tier ad networks just for redundancy purposes. Some people here are recommending you charge for your app right off the bat. Here is some advice which I think might save you a lot of time and headaches. Think of an app which you can write in a few days/weeks, but which has some roulette wheel chance of reaching your monetization goal. An example for me would be this Stopwatch app ( https://play.google.com/store/apps/details?id=com.unwrappedapps.android.stopwatch https://play.google.com/store/apps/details?id=com.unwrappeda... ), which I worked on for two weeks, after which I released version 1 of it. Then - promote it however you would have promoted your paid app. Then sit back and see. What's the response to it? Not that much in the way of free downloads? You're giving it away for free. Think how much higher the bar will be if people have to ante up to use the app, even if it's 99 cents. People will also have higher expectations - it's not some free thing they tried - they're customers who paid for it.