If you get stuck and you only get three of them, that’s okay—just move on. I would use a spiral-bound notebook or a legal pad and just move on to a different page. At the top of the page, write what kind of bullets you’re writing. Again, if you get stuck, don’t worry about it—just keep moving.
If you go through all twenty-one with this exercise, you’re going to have twenty-one pages: some with ten bullets, some with two, some with five or seven, but you’ll end up with many more than 100 bullets, and you can go back through and look at what you’ve written.
Pick out the ones that you think are outstanding and start migrating those to a different list. You will find you have a variety of bullets to choose from. I would suggest then you simply mix them up and group them on the page. I think it’s most effective to break up your bullets into segments of ten or fifteen in a section on your page.
Instead of having fifty bullets in a row, I would break that up into five different lists of ten bullets each, using different bullet types in each of those sections of your copy, breaking that up with different subsections of your copy and paragraphs so the flow stays even. You don’t want the flow of your copy to appear jagged.