1. Bike Gear
Lights (on the front, back and sides of your bike) are really important in the rain. Bells help communicate with other cyclists and pedestrians in poor visibility. Fenders for your bike help you avoid being splashed in the face and up your back. Bike Seat Covers or a plastic bag can be used to keep your seat dry while it's parked outside.
A waterpoof rain jacket (with armpit zips for longer distances) or a stylish rain cape will keep you dry without overheating. Rain pants are useful in heavy rain and regular rain boots or shoe covers will keep your feet dry. Put your hood on under your helmet to keep your hair dry. If it's raining heavily, wait to put your make-up on until you get to the office (or wear sunglasses to protect your eye make-up).
3. Carrying Stuff
A waterproof bike pannier that attaches to the back of your bike will ensure that your laptop, work supplies and any extra clothes stay dry. If you have a basket you can also get waterproof covers for them.
Plan your route before heading out to make sure you're taking the best option. Google Maps offers cycling directions or go to bikehub.ca for municipal bike maps.
Take your time and enjoy the ride. Don't be afraid to bike slowly or even pull over to let a downpour pass if you happen to get caught in one. Get your breaks checked and use caution when breaking in the rain as slippery conditions mean you won't be able to stop as suddenly.