Here we're going to see how to model with metaballs, it's a quick and quite easy way to create organic shapes.

Let's start, push space/add/metaball in your front view (key 1).
A ball appears (switch to shaded mode to get a better view : Z key).

In the edit mode (F9), you can change the mesh subdivision (Wiresize), it's quite handy because the less polygones you have the better way you can manipulate your object. We can give a small amount of polys (Wiresize) on the screen and a higher subdivision for the rendering (Rendersize).
Threshold allows to get higher balls (ou or smaller ones).

Metaballs allow you to "melt" balls with each other in order to create organic shapes.
To undersatnd how they work select your first ball and make a copy of it (shift d) or create a second one (add,space,metaball), you then notice when moving it that the two balls join and create a new shape.
The goal here is to play with the balls in order to create the desired shape, the tools you have to use the most are the "move tool" (g) and the "resize tool" (s).

It's a fun and nice way to model but it's quite slow and hard for big shapes.
Here is my first attempt at modelling a character with metaballs, you can download it in the download section.