I found this information on the Sonlight Forums and I thought I would post it here, for my benefit of reference as well as for others. I use some of the ideas already, like writing in the answers when my ds5yo gets tired of writing, or letting him just tell me the answers. Stickers would be so much more fun though!
I'm on my third child using ETC, and I thought that I would share some of the tricks that have made it more fun for us:
1. If the child is on the young side, it is OK to skip the writing stuff.
2. Using colored pencils or crayons to fill in the answers brightens up the book a lot.
3. Stickers (or stamps or colored pencils or markers...) can be used to fill in the little boxes. (Some of the questions are mark the yes box or the no box, others are mark this box if this is the right sentence.)
4. On the page where the child fills in the blank using words from the word bank. You can use a crayon to mark a different color in each blank and then have the child circle the right word in that color instead of writing the word in the blank. (See #1)
5. On the spelling pages, you can use letter stickers, letter stamps, or just take dictation. (See #1)
6. ETC does not work for every child, and if it is not working it is OK to drop it and try something else. (...and it is OK to come back to it later if you want to.)