I have my journal available within my editor, so it's easily accessible. I find that once I've seen how useful past-notes have been its very apparent I need to update.

I keep a standard set of headers for each new entry:

    * DD/MM/YYYY
    ** Admin
    ** Meetings
    ** Tickets/Stories/Work
    ** Problems

I copy/paste that header to the end of the file, and just fill out stuff as I go. I used to have my editor auto-open the diary on startup, but took that away in the end.