There are many method when come to cake decorating, from fresh cream, butter cream, icing to latest fondant.
We can divide into 2 main category cream and fondant.
Cream- Wilton Cake Tips chart and usage
Fondant flower
Fondant Android robot
How to pipe a butter cream rose
Fondant rose
Others links:
http://www.youtube.com/watch?v=Z5vsaRlBDuU
http://www.youtube.com/watch?v=75g12YqpsNY
http://www.sugarcraft.com/catalog/misc/tipusage.htm
Fondant Cake decorating idea:
nemo cake
http://www.cakeswebake.com/photo/4635016:Photo:362789