Silhouette Studio is the free software for use with the Silhouette Cameo and Portraits. It is vector based, which means that the graphics are lines or curves which can be scaled to any dimension without losing accuracy. This is different from a bitmap pixel based program for images such as photographs which will look blurry if an image is enlarged too much.
The software comes with all the basic functionality you'd expect. A good example project, in which I use a fair few of the basic tools to good effect, is the 'Sew Fabulous' paper cut that I completed recently.
Sew Fabulous project
Simple shapes and the scale window
The Silhouette Design Store
I used the Offset tool to make the lettering slightly bolder and therefore stronger in the paper cut design. Just a 0.02cm Offset can make all the difference. The Offset tool also welds together the letters into a which is handy.
Unlike the Make tool, once Welded, the shape can only be reversed back to the individual components using the Undo button. For that reason, if I recommend that they are just grouped (Ctrl + G or right click> Group) until near the end of the project, or a copy is taken before Welding.
Cut and Frame