I use a Filofax Pocket diary to log advance events, everything from bin days, to appointments, to payments due in or out (what time-management author David Allen calls the "hard architecture" of your calendar) and these Pocket Year Planners, folded to the current month with a small clip, make the perfect month-at-a-glance overview to go directly in front of the main diary section. It allows me to add small personal notations and icons which show that something awaits inside the diary on that date, as well as giving advance notice over a longer timespan.
Because I often have to change advance plans, I use a 4B pencil, which obviously writes in grey, so prefer cotton cream for the inserts because it warms up the overall look of my pages. It's also portable, allowing me to carry a calendar of my basic commitments outside my home, without revealing too much personal data. Fantastic product, which has an almost Tardis-like ability to hold lots of vital information within a tiny footprint.