Because four-way independence -- or moving all four limbs at different times -- is so difficult, it is important to get started right away. Begin by keeping quarter notes with the left foot on the hi-hat. Add the bass drum on one and three and the snare drum on two and four with your left hand. Then add quarter notes on the ride cymbal with your right hand. Use a metronome and practice this at different tempos.
Practice the same exercise as Section 1, only move the patterns to different limbs. For example, instead of playing two and four on the snare, play it on the hi hat. Play the ride pattern on the bass drum, etc.
Keep doing this until you can do all possible patterns with every limb. This will help you free your mind and be able to do multiple things at once.
If you are right-handed, you will naturally have a right-hand dependency. This means your left hand will be weaker and won't be able to do the same functions the right can. Breaking this problem early is important. Start by playing an easy beat such as quarter notes on the ride cymbal, two and four on the snare and one and three on the bass drum and every four measures or so, hit a crash with your left hand. Resist the urge to hit the crash with your right hand, and rather keep the ride cymbal going. In time, this will become easier and easier and give you more options when you play.
Begin by playing quarter notes on the ride cymbal and one and three on the bass and two and four on the snare. Begin playing fills on the toms with only your left hand, keeping the ride cymbal going for time. This will help you develop your weak hand. If you are left-handed, reverse the instructions.