@Tiles :
In fact that's lot of practice, there's no secret

You want to do good models: practice modeling.
In fact you must find the best simple tutorials that will guide you.
For modeling Jonathan Williamson have done some great videos for blender and he has done some DvDs, and there are also DVD training for Blender !
Effret character And modeling a character by loops is very easy :
Just follow this tutorial :
Low poly character modeling After that you'll have a good base and you will be able to modelise even with Xsi or other modeler if you understand the way

Anothe rway is to scultp the character and use retopology to make a low poly one !
3D Coat retopology It can help beginners , caus sculpting is lot more natural and easy than drawing loops or faces !
In fact it's lot of practice not only tools !