As with many other skills, translating your ideas and insights into formal notation (a.k.a. "writing") comes more naturally in some people than others. However, as with most skills, you can improve by practicing.
You can start by rewriting proofs that you have already read or definitions you already know. Read what you write and ask yourself if you can understand that. If you don't, try again. Keep your language as simple as you can, and try to go to the point (be direct). Also, ask yourself why you can understand certain books or papers more than others, and try to capture and emulate their style or simplicity. Once you can say "this is readable", check the spelling, grammar, punctuation, repeated words and other details that you can correct or improve to make your text easier for the reader. Then, for a final test, you can ask colleagues/classmates/professors to read some of your writing exercises and to give their opinion on the quality of the writing.
If what you want to write involves many ideas, try to decide which are more general and start with those before going to specifics. An exception might be when a specific notion (some intermediate result, usually technical) is needed before continuing to other results. In books and papers this is sometimes called "lemma" and it comes before a theorem, because you use the lemma in the proof of the theorem (and probably never again).
Finally, I completely disagree with you when you say
It might be because (at times)I am not aware of enough literature in the problem domain and so have the problem of expressing my ideas.
Not knowing enough literature is perfectly normal when you are approaching a problem or a topic that is new for you. Problems with expressing ideas have more to do with lack of (or misuse of) vocabulary (not necessarily technical!) or the way you structure scattered thoughts into a hierarchy. Whatever the case, you can improve by reading a lot and writing a lot.