Because the blank page can deter me from even starting to work in a new journal, I get rid of it as fast as possible. I pull out the paint and slap it onto the pages.
My method is to choose a color randomly and apply it rather haphazardly to a few pages spread throughout the book. I prefer Golden Fluid Acylics with plenty of water. Then I switch to another color and keep going until all the pages are full. The entire process for this 68 page journal couldn't have taken more than half an hour. Don't think; just do.
Eventually in the process, I start adding second colors to a page, and I add a few bits of metallics here and there.
You can see that I make no effort to get a uniform color on the page. In fact, I much prefer there to be some underlying structure, and I create it deliberately. I know I'll be adding more color to each page, so I keep them relatively light in value.