Just write.
Sometimes it may be wrong but just getting started and showing up will lead to improvements. It takes lots of thinking sometimes just to write a decent answer to a question. Once you get the hang of it, it becomes easy. Don't copy what you answer from an answer that has been made by others. Don't answer those questions that your not familiar with. It will be rather difficult.
Read more and don't do it for the money but rather for the passion to get the message out instead. Polish up your English language use like the understanding of the structure and learn more words to built up your vocabulary so the reader understands your answers. Broken English or the poor command of the language leads to usual pain to read like watching a bad director crafting his boring movie which has not been properly done of due to lack of directing skills.
Just keep practice writing.