Strictly speaking you can make do with items that most people have around the kitchen if you have to.
However to get the best results you will want to have the proper equipment.
The most important tool that you will need in order to be able to decorate a cake is a spatula.
While it is possible to do it with a regular kitchen spatula you will find that it is a lot easier if you have one that is designed for cake decorating.
The reason is that one of the most difficult parts of cake decorating, at least for beginners is getting the icing flat.
The best spatula for the job is one that is long and thin and has a curve between the blade and the handle.
This will allow you to get the spatula to lay flat which will make it easier to get the icing flat.
The next thing that you will need to decorate a cake is a pipping bag.
This is simply a bag with a hole in it, you fill the bag with icing and when you squeeze it icing will come out of the hole.
This will allow you to put all of the fancy designs on the cake like edging and writing.
You can make your own pipping bag in an emergency by using a plastic kitchen bag and cutting a hole in corner but it will be a lot easier if you have a proper pipping bag.
In addition to the pipping bag you are going to want to have tips to go with it.
These will allow you to change the shape and size of the stream of icing that comes out.
There are literally hundreds of tip designs that you can get and if you are serious about cake decorating you will likely collect quite a few of them.
If you are just starting out you can get them in a package that has several different tips, this is the cheapest way to get a decent variety.
The best way to get all of the tools that you need to decorate a cake is to buy a kit.
There are lots of them available ranging from simple ones that can be purchased for about twenty dollars to others that include all kinds of fancy extras and sell for well over a hundred dollars.
How large a kit you need will depend on how serious you are about cake decorating.