Prepare A Writing Structure. You can't just start writing the answers without knowing what points should be covered. The most general structure is to write introduction then write the points/paragraph required.
Don't Be Too Generalized. Remember you are writing an answer and not a novel. Don't be too philosophical or generalized while writing the answers.
Improve Basics Like Tenses, Grammar, Etc. Whether you are attempting UPSC exams in Hindi or English, Grammar is very important.