After the game is made...

Hi everyone!

This is my first post and it it's in the wrong section I apologize in advance.

Decided (like so many others) to make a game - have it in Apple Appstore and Google play.
Then I re-thought it and decided to make a much, much smaller game - a Duck Shooter or something like that.
The game itself is not that important - the process is.

The reason why I want to make a really small game is to be able to go through the whole process of making the game. From coding to publishing. I'm not thinking about marketing here, rather all the pitfalls that comes between finishing the game and having it out there on the appstores.

So what I am looking for are tips, advice, war-stories when it comes to building for different platforms in Unity, regestering and setting up accounts (and all the hassle that goes with that) and perhaps other things that I haven't thought about.