User Experience Research Techniques for Instructional Design
Rather than guessing which designs will work better for users (which we do a lot of in L&D), borrow techniques from UX. Connie Malamed summarizes multiple UX research techniques. Note that a lot of UX research can be done pretty cheaply and simply. You don't need hundreds of people to test for many of these. Small scale usability testing with 4-6 people can give you useful results.