Most of the times, authors are unable to move beyond the first chapter of their book only because they keep rereading it and keep making changes to it, to the point that the process become extremely frustrating. What they need to understand is this is just the first draft and all that need to be done at this stage is to write; good bad or ugly, that does not matter.
What we read of our favourite author is the final draft that has gone through rigorous cutting, chopping , adding and much more, to reach to that stage, and comparing our first draft to their polished work is impossible. Even the best of authors have written horrible first drafts, but the point is that they have written them; we need to write horrible drafts to move beyond that mental block.
Even when we know these facts, it is difficult for struggling writers to move ahead, this is when you need to come up with a strategy to break that ‘mental block’. Some call it an ‘in-depth’ outline, which just narrates the story in detail, with finer lines to the characters. When you are stuck at a point or cannot get yourself to write a scene, all you need to do is put down a note there saying ‘fight scene’, or ‘proposal scene’ and move ahead to complete the first draft.
Make yourself believe that the first draft does not matter, and all that matters is that you have something to build your novel on. As you continue writing you will find your story taking a shape and probably changing a little than what you had expected, but that is alright; if you have the end in mind, you will reach to it, even if the story takes a different shape.
At some point, you might also feel as if some of the parts that you had written earlier have now become irrelevant and you would want to go back to it and change it, but don’t do that, just finish your draft. You will always have time to revisit each and every part of your book and make changes, but for now all you need to do is write. No matter how many changes you make to your fist draft, there are high chances that you will make substantial changes in the drafts to follow, which will make these changes irrelevant.
The most important thing to remember about the first draft is to have a draft, horrible or not, you need to have the first draft to make it the base on which to build you bestsellers. Once the entire story is on the paper, it is easier to change it, refer to the characters and build them, but if you do not have a first draft, you do not have anything to work on. It is the concrete on which to build the rest of your novel, which will become less horrible with subsequent drafts.
The bottom line is to write and complete the first draft.