This year, my oldest is keeping his own lesson notebook, and it is divided into sections for science, history, writing/grammar/literature, vocabulary, and math. His notebook is similar to mine, but without all the extras I include.
It's not rocket science, but it makes staying organized much easier. I bought him a notebook with a built-in pouch in the front to store his lesson CDs for math and science, and there is plenty of room in the notebook to add more sections and pages as we go through the year. I made copies of the tables of contents from each of his main books and put them behind dividers for each subject. When he completes an assignment, he checks it off, and things like essays and quizzes are inserted behind each schedule. Because we "do school" year-round, once a level is completed, I remove the pages from that section and add in the new schedule pages.
In a separate notebook, he has a book list where he writes down the title, author, and number of pages when he finishes a book. He also has a movie list to record and critique all the movies he is watching for his film class. My son is learning to keep himself organized and to be responsible for keeping up with his own assignments. As he transitions to high school work, he is learning to both work independently and know when to ask for help.
One "trick" I have implemented this year--My son got his own computer for his last birthday, and he would rather do things on the computer than "by hand." I email his assignments to him, and he sends me emails with his essays and other written work attached. Even though we are often in the same room, he enjoys getting emails, and it's an easy written reminder for him from me. He recently had to rewrite a page from his Grammar and Writing book, correcting all the errors in the paragraphs. He asked me if he could just type it and send it to me instead of rewriting it all by hand. I obliged, and when he sent it to me, he commented that he turned off the spelling/grammar checker before he typed it. Duh! I wouldn't have even known--I didn't think about all the "helps" the computer gives. Back in my day, we didn't have all these new-fangled gadgets...