This might be common sense, but before you embark on your journey, I find that doing the following often proves to be quite useful:
1. Find out the visa requirement.
Once you've decided on a destination, you need to find out if you need a visa in advance or not. For Canadians, you can find out if you need a visa at Government of Canada's Travel Advice. Click on the destination country then the Entry/Exit Requirements tab. Also, you can use the same site to register with the Canadian Government so they will send you emails regarding the current situation of the country you're going.
2. Do a bit of research!
It's always helpful to know a bit about where you are going. Doing a little research beforehand goes a long way when you're away. I always Google Map and Google Image the destination. I also do a quick search and read travel forums to see if the destination is safe or not and what to watch out for.
It's good to get an idea of what attractions are worth-seeing. I usually search the destination on tripadvisor then click on the Things to Do tab to help plan my trip. Of course, Lonely Planet and other sites also has a lot of info.
It's also important to know what the weather is going to be like. Is it wet season? What's the temperature? This helps you make a decision on when to go where and what to pack. An awesome destination could suck if you're there at the wrong season. I usually google the [ destination name ] climate.
Another thing to do is to find out the currency conversion rate in advance! You can get this as an app on your smartphone or iPod/tablet and avoid doing complicated math when you're trying to buy something abroad.
3. Book flights & accommodation
I use KAYAK to check out prices, but sometimes it's cheaper to book directly from the airline. Make sure you do a quick Google search to find the flight safety records for the airline you're flying with.
Usually I use either booking.com, agoda, or airbnb and see which has the best deal. Sometimes the hotel site offers a better rate! It might be helpful to read reviews of the hotel on tripadvisor and also print out the map with the hotel the address and phone number in case you can't find it.
Although it's not a good idea to over pack, find out weather things you need are available where you are going. For example, it's hard to buy tampons in some countries. Pack light but make sure you bring things you can't get. Weigh your luggage before you get to the airport to avoid paying overweight charges.
If English is not widely used in the country you're going, write down a few useful phrases on a small piece of paper and carry that with you. For example, how much is it? Thank you! Sorry! Also, find out what local dishes are a must-try and write down the names in case you arrive at a local restaurant without an English menu or a picture menu.