Here are some tips that may help get you started on cake decoration.
Wilton offers cake decorating courses at local Michael's stores. Different stores will have courses at different hours. In general it's a one-month course at either weekends or week nights. It will be four two-hour sessions. Generally each course costs $25. Sometimes they offer sale prices like $12.5 for the course, plus you can bring a friend.
When you register for the course you will be provided with a list of tools to prepare and you need to purchase the course kit. Scrap the 10% off coupon offered with course registration - print a 40% or 50% off (one regular priced item) coupon online from either Michael's, AC Moore, or Jo-Ann's.
Any other tools may be purchased this way. Or if you are sure you want to follow the whole path, you can get all the tools from a tool kit set with the box.
Cake decoration is a hobby, and like any hobby, it rarely saves you time or money. Rather, it consumes both. So, don't be surprised if the tools can turn out to be quite expensive. And yes, they have been rising the price over the last couple of years.
There are 4 levels of courses:
I: Buttercream
II: Royal icing (and maybe something else too? I didn't take this one)
III: Fondant
IV: Fondant and gum paste
For those who think buttercream tastes horrible, push the icing off your slice of your officemate's birthday cake , and only enjoy whipped cream, NONE of these courses would help you at all. You may still want to take "course I" to get a general idea of how things work. But personally I think any online video search can give you enough information to get started.