mark is right, the problem when people think in aimation, they try to create a frame by frame thing that really dont work. You need to planning your sequence using a storyboard or you will do a lot of unnecessary shots and animations.

After the storyboard is done you can start to calculating time, every action need to have a time, so you can calculate how many frames it will have.

Now with you time sheet you can start to create animation blocks, that will be used as clips, but not a frame at time, but try to see where the movements change and create the master keys, let Carrara do the inbetween frames for you BUT you will need to back and adjust them after all o get a more smooth and realistic transition.

In general in a big studio, they first move the character as a block throught the space (scene), after that they create the master keys for hip (gravity like Mark said), after that legs, arms and other parts. The key is adding details, like in modelling.

Other thing that is very very important in animation is antecipation! You need to understand this very basic idea: an arm never goes up without down a little bit! Antecipation is very easy: before animate, go in front a mirror and do YOU the movement! This way you will see how your body really moves.

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