If you have a new app in app store the first thing to do is ranking it (using keywords rank)
also you will need a good amount of installs
and then when the user find your app and click on it the first thing he will check is the rating
so today i will tell you how to get all of that for free
1-register here (get 20$ free)
2-after signing up you will get 20$ in your account :
3-after that go to ''Add Application" then "Add new app'' insert your app then click ''Promote''
everything is clear up to you to choose want you want :
Tips :
don't creating muti account = insta ban !!