The first step is probably the most difficult one for me. It is...da da da da! Sketching!
Drawing out the contour lines is the most important step because it allows you to see where the color will be placed later. It takes the most time, especially if you choose to start learning the way I did.
If you are trying to get better at realistic drawing, t would suggest the grid system method. This method has been utilized by artists for centuries. While artists had to create grids with instruments back in time (like Van Gogh's grid system), the benefit of modern technology is that this can be done virtually over an image.
I use Photoshop to create a grid layer over the original image, and then create the same grid over a smaller paper or larger paper. Doing this method helps me to focus on the contour lines themselves, instead of the overall image. By breaking down the piece, it will help any beginning artist to have less detail to focus on by breaking up the details within the grid.