Drifting can be a very tedious and difficult feat to achieve. Some consider it an art, while others consider it recklessness. This is just a game, so pick up your paintbrush!
"Drifting refers to a driving technique and to a motorsport where the driver intentionally over steers, causing loss of traction in the rear wheels through turns, while maintaining vehicle control and a high exit speed. A car is drifting when the rear slip angle is greater than the front slip angle prior to the corner apex, and the front wheels are pointing in the opposite direction to the turn (e.g. car is turning left, wheels are pointed right or vice versa), and the driver is controlling these factors." (from Wikipedia) Drifting is caused by a lack of traction to the rear tires. The spinning of the tires causes the vehicle's rear end to "swing" out causing oversteer. Different cars will behave differently due to differences in torque, tire tread, weight placement, and suspension recoil. The spinning of the tires also "pushes" the back end of the car forward, so once in oversteer, it will need to be controlled.
Initiating a drift
There are a number of ways to get yourself into a drift. As said before, weight placement and suspension recoil can affect your traction on the rear tires. Here are some techniques:
Probably the easiest thing to do, but, however, most cars in the game do not have strong enough braking to do this. Just activate the handbrake and it will cause your car to lose traction.
Steer + gas
Ride your gas at a moderate RPM and steer into the corner. Once your front end starts turning, give it some more gas and you will get into an oversteer.
Use your suspension to "jump" the car into a drift. Steer away from the corner quickly and steer back in. This will cause a bouncing effect from left to right (or vice versa). Apply the "steer + gas" technique to get into oversteer if not achieved already.
"Dip" your back tires in the dirt or grass or whatever off the track. This will cause your back end to swing a bit.
Controlling the drift
This is simple to do, but hard to perfect. Essentially, you will only need to steer to get your wheels pointed the direction you want to go. You will also need to control your throttle. The slower your tires spin, the more traction you will have. The opposite happens with faster spinning tires. Control your throttle and be careful not to give it too much juice or you will most likely spin out. Spinning out usually happens when the car is oversteered too much. The tires keep spinning and your car continues to rotate into the turn, but the front end will have too much traction and cause the car to rotate more.
Some cars are easier than others to drift in the game. Excessive oversteer can be a problem for beginners. Lots of torque and traction make initiation and recovery easy.