My design process usually starts out with a couple extremely rough first drafts that I use to decipher the flow of the project.
After those are established I will create a more defined sketch layer on top of all of the other layers so I don't lose the originality of the first couple layers.
Once I like the sketch I will go in and create a line-art layer that will solidify all of my lines and make it so all aspects of the piece are clearly defined.
Color is my last step and I will spend a lot of time on this closing stage trying to find the best palette and overall feel for the project.
Adding in textures and overlays are additional and sometimes optional depending on the piece but its usually the last and final step before I deem a project complete.
And there you have it! My design process!