Notebook pen loops
Sacha uses her notebooks almost exactly like I use mine. One thing she mentioned was finding a way to keep her pen/pencil with the notebook. Here's my favorite solution. Duct and gaffer tape look best.
When I have cheap/slim pens with clips, and don't mind looking a little scruffy, I use the pen's clip like a paper clip between the page I'm on and whichever cover is nearest. It makes for the fastest notebook opening time ever.