At my age, I have problems remembering every lyric line from even my most practiced songs. Since I also have poor near vision, I use 8.5 by 11 paper with 14 or 16 point type and put the paper into clear plastic (non-glare) page sleeves with holes for a 3 ring binder. I can move songs around between sleeves to put together prompt books of whatever combination of songs I have any possibility of being able to play. When I have the occasional volunteer performance to do, I can customize a song prompt book in a thin binder just for use that one time. If I were to try to carry every homemade song book that I've put together over the years, I'd need a moving van to transport them.

SC