I don't know my mistake, please advice me


Your Number#1 mistake is that you cant understand your mistake.
Said that, the problem is that you have not studied enough to understand and identify the issues you are dealing as a graphic designer and the quality the marketplace needs.

You need to start over. If you relay like to do this please take you time and learn.
As a quick advice you can focus on the following steps:

  1. Idea
  2. Typography
  3. Hierarchy
  4. Composition and colors
  5. Over all look an feel and impact
  6. Marketing