How can I remove the crayon marks on my walls?

Page 119 of Blind Dates Can Be Murder suggests the following steps:

1. spray the marks with WD-40 lubricant
2. wipe with a paper towel

If you still see some marks:

3. scrub with a washcloth using a mix of liquid detergent and hot water

And remember to:

4. rinse well
5. dry with a paper towel

Have a lovely day!