Elizabeth Berrien is arguably the world leader in wire sculpting. Using various types of wire---including baling wire---she has made two-dimensional and three-dimensional sculptures of people, dinosaurs, birds and mythical creatures such as flying horses and unicorns.
In instructing others on how to make wire sculptures, Berrien recommends baling wire because it is so cheap and usable. Baling wire is generally dark, but silvery galvanized wire is also available for purchase. Either way, you don't have to worry about getting the right color, since you can paint it. Remember that you can do interesting things by using various kinds of other wire in your projects along with your baling wire.
Wire sculpting is generally safe. However, many types of wire---especially baling wire---can pose the danger of suddenly whipping around and striking the artist or a bystander. Because of this, Berrien suggests that sculptors wear eye protection. In addition, in classroom settings Berrien strongly suggests that students use 12-inch segments of wire instead of whole rolls.
In teaching wire sculpture, many teachers like to give each student one or a few wires of a specific length and challenge them to make something out of just that. In a situation like this, aspiring artists have to really use their imaginations and do as much as they can with the little that they are given. It is probably important to stipulate whether you want them to make two- or three-dimensional works, as both are common in wire sculpting.
In 2008, Berrien did an advertisement campaign for BBC in which she used wire to make large two-dimensional pictures of events that often escape coverage by the general nightly news. These events include pictures of war and the distribution of humanitarian aid.