Here we are talking about ASO for Android / Play Store only and the tips are basic ones. There are many advanced ASO tips which are out of scope for most of the readers here.

Including the essential points only here which are the most important ones.

1. Keyword Research

Make a big list of keywords for your app well before the launch. Then choose the ones with high traffic. Make sure it is relevant to your app (Even though not 100%)

2. Use the keywords effectively

App Name, Short Description, and description field are important places to add keywords in Android. Remember that App Name and Short Description fields having more weightage than the description field.
The main keywords can be used multiple times (up to 3) in the description.

3. Choose the best category

Study the market well and select categories in which you could get to better Top chart positions. If the category is highly competitive, it will be tough to crack the Top 10 or Top 5.

4. Create best graphics

The icon should be unique, visually attractive, and related to your app.
Screenshots can have text to explain features. Featured Graphic can have bullet points of the major features of the app. Make sure to create a stunning promo video also. The Promo video should explain the app features clearly. It can be 30 seconds to 1-minute in length.

5. Manage reviews and ratingss

Always try to keep the rating 4.0+ because it is the minimum limit at which users consider it as a good app. Ask for a review at the right time. Always respond to good and bad reviews. Help and fix the issues regarding bad reviews and convert them to good reviews. Keywords in reviews help the app ranking. It is OK to ask your friends to include keywords in reviews.

6. Limit the app size

Make sure to limit the app size maximum possible. Below 20MB is ideal. It may not be possible always. But try to keep it under 50MB.

7. Have a budget for advertising

It is really important to spend money on paid ad campaigns. This will boost your organic installs. Plan to start and stop campaigns as per your budget and organic download volume.

8. App updates are essential

Try to update the app at least twice a month. Google loves updated apps and it gives a fresh boost for the app. You may experiment with keyword / graphic updates during each update to test the effect on downloads.

9. Play Store experiments

Execute Store listing experiments occasionally to improve the downloads/conversion. You can experiment with different versions of
Icon, Feature Graphic, Screenshots, Promo Video, Short description, Full description. You may get surprising results on a simple icon change!

10. Use a tracking tool

Make sure to track your keyword positions, installs, category positions, conversion rates, and reviews using any ASO tool regularly. Track your competitors also.

11. Promote in Social Media

Create backlinks in the maximum possible places and post regularly in all possible social media. It is proven that Backlinks help to improve ranking in the Play store.

12. Localize

Localize the app and the listing if you are targeting globally. It can be in phase 2 if on a tight budget initially.

13. App Usage

Do whatever you can to get the users back to your app more frequently. App usage is a really important ranking factor. It can be push messages, offering coins, special offers, login bonuses, etc.

14. Referral System

Try to include a referral system within the app that gives benefits to the user, if possible. Always try to design it in such a way that Referrer and Referee gets a benefit.

15. Give enough time to grow

Unlike iOS, the Play store ranking is more time-consuming. It may take 2 months or more to get your primary keywords to get ranked. We can boost the positions only after your app is listed under 250 for that particular keywords.

16. Improve the positions

The primary goal should be to improve the keyword ranking of all high traffic keywords and improve category ranking. There are many ways to achieve this other than the tips above. I will be writing another detailed article for the same. You may contact me if you need any specific details.

17. Get ASO Help

Try to learn ASO yourself. If you are too busy and if the budget allows, hire an ASO Expert to manage this effectively.

Note: You can discuss any other major factors in the comments section below.