Take good looking screenshots of your game on target device. You can hire experts for $5 to do it for you.
Hire an expert copy writer to write a good app store description. Approximate cost is around $20.
Get a Good press release written and published. There are many press release agencies. You should be able to find one for $50.
Get a good game trailer made. A good trailer is worth 1000 words. This should cost around $20.
You may feel that the cost mentioned are too low. You can get good freelancers for this cost on Fiverr.
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Apart from the paid strategies you should also promote your game in these forums which are totally free.
r/freegames
r/androidgaming
r/gaming
You need to have good Karma to promote on Reddit. But its totally worth it
If you have a good game then these sub-Reddits itself will boost it to the top charts. The users in these communities respond well to game links.
This is not a theory. We tested this strategy with a simple android game and a $100 budget.
We spend the $100 dollars in a slightly different way, as we had inhouse graphics designer. You can read the results from the link below.
Test Result
ALL THE BEST