One of the hard things for me is that I'm so tired at the end of the day I can't usually get much written out. So, I've taken to writing up some thoughts when they come to me, in the middle of the day at work - I type them on the computer and then I can print them out and stick them in my journal. Some weeks I've not used the journal book but just the computer.
It has also helped me to get the thoughts out of my head, so then I can get back to work