I keep a running list of tasks on the left page of an 8x10 notebook open on my desk, and I use the right page of the notebook for call notes, etc. Check the tasks off the list as they are completed.
I typically fill up the right page of the notebook with notes before I complete all the tasks on the left page so every few days I flip the page and start a new list. I rewrite several tasks as carry-overs, but it is a good opportunity to review the overall list and prioritize as necessary.
I tried other methods, but eventually stuck with this, and it works for me.