I actually don't fold my fabric when I don't cut across. I measure how much I need and cut that much off the yardage (with a little extra in case of wonkiness). Then I clear my table and using the appropriate ruler, I cut the width I need along the edge until all is cut. I usually don't cut the selvage until my strip is cut so I have to figure the selvage into the strip width. Lastly, I trim the strip to length.
Jeez - that sounds way more complicated than it is.