Speed Up at the Start
When the clock begins to count down at the beginning of the race, watch carefully, and when the number 2 begins to fade, quickly press and hold "A" on the Wii Remote until the race starts. You'll receive a small power boost that will hopefully put you in the lead at the start of the race.
Recover from a Wreck Faster
When you hit an obstacle and begin to wreck, press "2" right when you land to receive a temporary power boost. If you are racing on a cycle and get hit, pull up the Wii Remote or Wii Steering Wheel to perform a wheelie. The wheelie will help you to recover faster and quickly increase your speed.
Avoid Shell Attacks
To avoid red shell turtle attacks, put a banana behind you by dropping it or holding it in position. The banana will stop the red shell from hitting you. To avoid green turtle shell attacks, put a red or blue shell behind you by dropping it or holding it in position. The shells will collide with the green shell and you can continue on your race like nothing happened. If you are in first place, avoid a blue shell attack by using a mushroom when the blue shell begins to rise above you. This may be difficult to time perfectly to avoid the blast, but will get easier with practice.
Avoid POW Blocks
When you see a POW block coming at you, quickly flick up your Wii Steering Wheel or Wii Remote, and you may avoid it by spinning around. You'll lose your currently equipped item, but this is better than being hit by a POW.
Unlockables
In Mirror Class, you can race all the courses backward for an additional challenge. To unlock the Mirror Class, win a gold trophy in all of the 150cc level races. Get to race as Birdo by beating 250 people online, and unlock the Daytripper bike by winning 2,700 races. Beat the Normal Ghost by at least seven seconds to unlock the Expert Ghost for that course.
Receive the Gold Steering Wheel
Play a great deal of time with the Wii Steering Wheel and not the Wii Remote, and you'll receive a Gold Steering Wheel next to your name when you play online. When you receive the Gold Steering Wheel is random, but most users find that they get it after playing extensively with the wheel.