Whether you're looking to hone your already established cake decorating skills, or completely learn from ground zero, you'll find there are simple steps you can take to advance your decorating technique.
Practice, Practice, Practice- As with any hobby or skilled pursuit, you must practice. Once you have the basic tools and equipment, using them must become second nature. There are many different tips and frosting techniques, so try to start simply. Load up your favorite icing bag, and get out a plate or milk glass and begin practicing. Once finished simply scrape off the icing and reload it back into your frosting bags and start again. Practice is the single most important factor and it is not practical to bake cake after cake to gain the necessary experience. Another option is to bake a single cake that you don't intend to eat, and just keep decorating it over and over again.
Use Vibrant Colors- A large part of how a cake appears is due to the colors used. Be sure to use coloring gels as they produce a much more vibrant and vivid color. Look at pictures in magazines or online to get ideas about color schemes and practice making your perfect colors as it will take some skill to obtain the color you desire.
Imagine Your Finished Product- Once you are well-practiced, both with the actual laying down of icing and with coloring, you must begin to imagine how your cake will look. How many layers will it have? What is the overall theme? How do you want people to feel as they look at your cake?
Implementing these simple guidelines will serve to greatly increase your cake decorating skills.