How to Rank Higher on Google Play App Store?

My alarm clock apps got 100 download and about 50 active users right now, i have launched it about 7 days.
First of all, to rank your app higher on Google Play Store at the first place is very difficult, but fortunately, i know that some forum is offering Review Exchange service.
Some developer would send a private email to you and ask you to try their apps, and leave them a fair comment, mostly 5 stars review. They will do it in return to your app.
I think that it is a pretty good, fair and LEGAL idea to boost app.
Many apps are very innovative, interesting and deserve for more download and money, however, we all need to rank up in order to get more download. Exchanging review would be a good and free way to push apps ranking higher.
We should not heavily depends on this method, but as a starter, it is a good choice!
Why don’t we start a review exchange website for apps developer?
http://iammakingmoney.com/how-to-rank-higher-on-google-play-app-store/

 

That's fine but do you think that this is going to take you too far? I'd instead prefer improving the app to an extent that it reaches out to people by serving their requirements. I think that'd be more fruitful in the long run instead of adding efforts trying to manipulate the system.

And imagine what if tomorrow Google takes a notice of this and penalizes apps owners for manipulating the process. I don't want to even think of even doing anything like that.