Decide what your process will be and stick with it. Some writers prefer outlines to beat sheets, some use both. What time of day/night do you find most productive to write? All of these things are vital to successful writing. Write often and read a lot, even out of your genre. I have found a lot of inspiration in non-fiction for example. Finding your voice and brand will help you write with confidence, which is key. If you question your self, you won't get past page one.