Safety starts with proper equipment. It's important to keep your bike in good running order in order to be safe and comfortable on the road. You can maintain your bike yourself, or you can take it to a local bicycle store.
If you want a full tune-up before spring, it's best to take it in the winter (before March) when the shops aren't so busy. You need to do the following regularly (every week during the cycling season):
Tire Pressure: check your tire pressure and pump your tires to the recommended pressure (the number is embossed on the tire sidewall). Under-inflated tires make it more likely you'll get a flat and will also slow down your ride;
Chain: oil/wax/grease your chain (and preferably clean it if it's dirty). A dry chain will squeak and wear out faster and is more likely to snap;
Brakes: Check your front and rear brakes to ensure you can quickly and fully stop. This is essential to your safety. You should not be able to press your brakes right to the handlebars: if you can, that means the cable has stretched and needs to be tightened;
Shifters: Check that you can shift properly;
General upkeep: Check that all your nuts and bolts are tight, and that your tires aren't worn or cut or have glass embedded in the tread.
Learn to maintain your bike
If you want to do some of the maintenance yourself:
The Ottawa Board of Education offers bike maintenance courses. See the "Do it yourself" section of their General Interest Programs for details.
The Re-Cycles Community Bicycle Organisation (473 Bronson Avenue, south of Gladstone) is an excellent place to learn hands-on bike maintenance at a very reasonable price. You do the work yourself with advice and guidance from experienced volunteer mechanics. Re-Cycles also offer their volunteers access to free "Basics Night" courses, with one course taking place each month. See the schedule on their website.
Ottawa U. and Carleton U. have started several bike maintenance activities. Check with the sustainability department of your university. You could also ask at your local bike store if they're doing any courses.
Rightbike Community Bicycle Share in Hintonburg offers hours to work on your bike. Check their website for the latest.