Ok I just keep a diary, where I scribble stuff, which includes rituals that I have performed and rituals that I want to perform. It's not really decorated, and its not even organised. I dont even have a fancy name for it. It's just to keep a record of things. Something I may want to look at, sometime in the future.
But I guess that depends on how you feel. Just remember that you should feel connected with whatever you plan to decorate your book of records/shadows/light or whatever you want to call it.
If you dont connect to all the fancy stuff you do it, chance are you'll never get down to using it. Which kinda defeats the purpose of having it in the first place, doesn't it? If you don't understand symbols or feel disconnected from them, then please avoid going down that road, just because someone suggests it. What may work for me doesn't necessarily need to work for someone else.
Lol... I remember picking up a fancy book with handmade, scented paper. Thought it would be cool... I began writing in it and then for some odd reason, I just stopped. And finally found solace in something unassuming and less flashy. Something that wouldn't have a problem with me making doodles and scratching stuff out. At the end of the day, it's my book. I have to write in it and someday go back to reading it. I couldnt give a damn about what someone else would think ;)