First it’s good to buy android installs from different companies. Meaning if you want to buy them, might as well buy from the same marketing service provider like android promotion. The reason behind this is, if you find any fault or problem on the installs that you purchased you can always go back to them to ask for a refund or any correction actions from their part if you are not responsible for it.
However if you get them from different companies, you might fail to pick up which installs that causes you the problem (if there’s any). Other than that, you should be careful not to buy install from bots or spam installs. They might be cheaper compared to real users installs, but it has zero engagement value and might your app to be removed or flagged by Google.
If you are looking to buy Android game or app you should get them from real users and get higher chances of engagement. Other than that, it’s completely safe, because you get installs from real users that browsing over the Google play store regularly.
Other than that, you should ask and be sure that your question being entertained before making any purchase from the site. You should try android app promotion if you are looking the get the best customer service experience and you can ask anything related to the product and services that they are selling. Last time they are very helpful to me and the overall business deal is very pleasant.
Although getting installs is helpful to get you started and the time shorten there where you can further promote your app in other social media platforms, advertisement, marketing strategy and many more. Other than that, you also need to focus on polishing your app image or icon, keywords relevant to your app or game app, getting positive reviews based on customer service experience, users experiences and etc.