Place your important stuff, notes to your sub, your schedule, etc on your desk. Place a piece of plexiglass (or if you can afford it, a see-through desk mat on top). Use colored markers and color code grade level (or course, if teaching high school). Every day before you leave, make sure that area is clear so a sub can jump in if needed.
Under my mat I have: Color coded schedule, A note to the sub, The district, what to do in case of emergency card and my class counts (the number of kids in each grade level or by each day - so helpful when counting out supplies or making photocopies).
I have the rest of the steps posted for free over at Teachers Pay Teachers. Enjoy!