There are some self help tools available. Search the forums. I would presume that you are self applying for NIW petition. Be aware that NIW cover letters need to be drafted with great care as it might make or break your case and its the first thing that an officer will review. If poorly written, it might put him off. Plus, as you are probably aware, more than the actual merits of case, the presentation of it is more important as NIW are so discretionary. Really you should get an attorney to help you out if you can spend money. It will be well worth it.