When I was about 13, my dad was reading a book on mnemonic devices. You know, tricks to help you remember things. He taught me a trick to remember what page you are reading in a book and I have not used a bookmark since.
It's so simple. If you need to stop reading...just look at what page you are on, and reverse the numbers.
So, if you are on page 19.....say "91"' to yourself. When you come back to the book, you will remember!
It really works and it's easy! (Now it does get trickier with three digit numbers but I rarely read books that thick!)
That's my tip for you this Friday. Have a great weekend!