What is a good input method?

As more and more people enter to the Malayalam digital world, the issue of not having any formal training for Malayalam computing is more observed. People sometimes just search for input methods in web, ask friends or use whatever coming with the devices they have. Since I myself is an author of two input methods, sometimes people ask me too. This essay is about the characteristics of a good input method to help people make the right choice. This essay does not recommend any particular input method though. I will focus on Malayalam language, but some concepts may be applicable for similar languages.

This is a companion discussion topic for the original entry at https://blog.smc.org.in/what-is-a-good-input-method/