Hello guys, i notice most people create free apps while others create paid apps. so am asking how does one knows if the app should be free or paid after creating the app.

Having published apps for both free and paid, you will get about 5% of users if you start charging for apps.

Test it out. Set it for free for a week and paid for another week. That's what I did and I found out that setting it for paid gets me more revenue. This isn't always the case but is the case for the particular apps I put out on the market.

That's generally speaking true for iOS. On Android, you are not allowed to have one app that can have a price both of zero now or some other price later. In Android, it is either free or paid for and you cannot switch from to another and vice versa. People usually make free apps with lots of ads and then offer the same app for a buck or so without any ads. There may be many more strategies to this. On the positive side, Google Play lets you know how many downloads of an app have there been and then you multiply that by the price and see that some Android apps are making healthy amounts of money, say, in lower five figures. If you have an idea for an app, visit the Play store even if you want to publish it only on App Store; from the statistics in the Play store you will be able to see whether there is a market for your new app or not.