You don't want to find out in the middle of a ride that your brakes aren't working properly. There's little that can be done to fix these problems once you're on the road. Start out by spinning your front and back wheels separately, elevated off the ground. Apply each handbrake to make sure that the calipers and brake pads squeeze each side of the wheel evenly.
If the lever comes all the way back to the handlebar before the wheel stops, you'll need to check the brake pads and the tension on the brake cables. If one side of the calipers contacts the wheel before the other, you may need to re-center the calipers, which can usually be done by simply shifting it over with your hands.