Patent licensing has the opportunity to be much more lucrative than simply selling a patent, particularly for the small percentage of inventions that become widely-used products. If you decide to license a patent, you will have to go through three basic steps.
First, locate companies who may be interested in buying your patent. Looking at companies to whom related patents are assigned is a good place to start, particularly if you already have a list of related patents from performing a prior art search.
Second, you must convince the company that your patent is worthwhile for them to buy. This may be the most difficult step of the process, and could involve extensive product development and marketing that may be unfamiliar to most inventors.
Finally, if you find a company who is interested in your invention you have to negotiate a licensing agreement. Unless you have extensive experience in this area, the help of a good attorney is highly recommended to avoiding some of the many legal pitfalls of the licensing process.