Soon after I buy a car, any make or model, I add roof racks. Good roof racks are expensive, reduce gas mileage slightly, and are absolutely essential. Thule racks are nice and fit most cars. I've bought mine from L L Bean, REI and local dealers. If you buy them on-line, there's a rack fitter program that calculates the components needed for your make and model of car.
I've always used roof racks for my canoes. It's the most secure way to carry a canoe. They do make foam pads that attach to a canoe's gunnels. Even used them a time or two in the past. They worked well enough for short distances, but I would not want to carry a canoe across the state with them. (and NH's a small state)
I carry a lot more than canoes on my car: lumber, pipe, skis, furniture, bicycles, sailboats, firewood, and even a guitar once. Anything too long for the car is fair game for the roof racks. I made a plywood platform that straps over the racks and makes a good place for luggage.
Good roof racks can carry things that won't fit in a truck. Most truck beds are 6 - 8 feet long. Try carrying a couple 16 foot 2x6's with a truck. At best, it's awkward. At worse, it's down right dangerous. That's why I built full sized racks on my truck. Items can stretch out over the cab. Long, well tied lumber can easily be transported on the racks. My canoe's 17'4" and travels fine up there.
Avoid bungee cords. They have a tendency to stretch at the wrong moments. Once saw a canoe fly off a van's racks. The van hit a big dip in the road and the jolt stretched the bungee cords until the boat slipped off the racks. It was ugly. Smashed a side window on the van and busted up a fiberglass canoe.
Some people swear by adjustable strapping. They aren't my first choice, but I'll use them in a pinch. If you decide to tie loads down them, make sure the hooks have secure places to attach and that they can be crank down tight enough. Avoid the cheaper ones.
My first choice is good synthetic rope. Nylon and nylon blends work well for most things. Get a large enough diameter that it has some strength, but not so large that knots are difficult to tie. Learn a few knots. Most thing can be tied down with a couple simple half hitches. There's about a half dozen knots that I use, but two half hitches- tied right, should take care of 90% of your needs. You might want to brush up on your Boy Scout manual and learn a few knots.
I recommend checking your load after you go down the road a few miles. Rope can stretch, especially brand new rope. On a long trip, it might be necessary to tighten your ropes a time or two. Make it a habit to check them when you stop for other things -fuel, food, rest stops, whatever.
On my car I've gone though the trouble of installing heavy duty eye-bolts on the underside of the bumpers -2 in the front and 2 in the back. Long items like lumber or canoes need to be tied on the ends. It keeps the load stable.
Here's how I tie down a canoe. First tie down the middle of the boat where the roof racks are. After the middle, The bowline is tied to the front bumper. It's tied fairly tight. The idea is to keep the bow of the canoe nice and tight to prevent wind from getting up underneath it. Last, tie down the stern of the canoe to the back bumper. If the stern is tied first, it tends to raise the bow some and it's likely to wobble from side to side.
If space inside the car is limited, the paddles are tied down next to the canoe. I've even stuffed tents, sleeping bags, and a big dry bag full of clothes inside the canoe. Of course, everything has to be secured. The seats, thwarts, and roof racks are good tie down points.
One could use a utility trailer to carry all that stuff but there are advantages to the roof racks. A trailer has to be registered. There's more things that can wrong -wheels, springs, lights, hitches, etc. A car without a trailer is more maneuverable.
Keep rope in your car. You never know when you might want to take something home. I bumped into one heck of a deal on a contractor style wheelbarrow. Bought it and took it home on the roof.
34 minutes ago