During my brief time as a substitute teacher, I found that the best days came when I subbed for a teacher who was very well organized. When a teacher is known for being organized, it is likely that she will not have any difficulty finding a sub. Teachers who did not have detailed instructions or did not leave any instructions at all for subs had a hard time getting one in the future.
I have 2 separate files. The first comes in color, and can be printed out a laminated/put in sheet protectors.
The second is just in black ink. This can be printed on special paper or printed on white paper and then cut out and pasted on special paper.
These are the things I looked for as a substitute!