Choose the quality you want your brand to embody and then think of things that embody that characteristic. For example, Iron Mountain is pretty much just a document shredding company. They chose that name because they emphasize how secure their processes are as opposed to how fast, cheap, or simple they are to work with. If you want to emphasize how "sexy" your product is then emphasize that. If you want them to be "fun" then go for something that embodies that. The same goes for quality, inexpensive, comfortable, etc.