What is the best way to develop icons in Android applications?
If you are using IDE Android Stúdio it already has a tool that converts image to icon ... in this case you go in:
right button in the app > New > Image Asset (there you import the image and it already converts to icons) I hope you helped!
It's at Phophotoshop
It is a professional program and in it you will have all the necessary tools to be able to produce professional icons.