If you'd like to create hand-lettered printables, consider taking a custom lettering class so you can edit your designs in Illustrator. Hand lettering is an excellent way to make a printable truly custom.
Another handy tool for printable assembly is a score board. You'll use it to make creases in paper for easy and precise folding. Don't feel the need to buy all these items at once. It takes time to acquire all the tools for printables, but in the end, you'll find that the investment will be small for a fun and creative hobby or business in printable design.