These quick tutorials will introduce you to some of the many fundemantal tips and tricks when animating a character. It's worth noting, that there are many fantastic resources available on the internet, and in particular in print that will introduce you to, and enhance, your character animation.
It's well worth checking out both 'The Animators Survival Kit' and 'The Illusion of Life'

These tutorials make use of the free character rig 'DummyMan 1.0.2' available from highend3d.com.

Shifting weight
One of the keys to animating is being able to shift and transfer weight. This video looks at a simple example, and introduces you to some of the things you could do when animating to take away any unwanted robot movements.
Launch Video (2m 46s)

Fundamentals of a walk cycle
Getting a character to walk is simple, if you firstly define the contact points, and the passing position. This video tutorial will show you how to get your character walking in no time!
Launch Video (12m 28s)

Walking examples
So your character is walking... time to add a little personality to that walk by adjusting some of those keyframes. This video will show a few quick examples of the same character walking differently, giving you a character within the character!
Launch Video (4m 39s)