It's best for you to learn ruby on rails or DJango. They will add lot more extra value to your freelance job field. In addition, always learn new things (language, framework, techniques, tools etc) if you want to stay in software development field. If you need any guidelines to get started with freelancing I recommend to read following article http://webindream.com/freelance-how-start-freelance/

Answering to your last question: it's best for you to learn ruby on rails or DJango. They will add lot more extra value to your freelance job field. In addition, always learn new things (language, framework, techniques, tools etc) if you want to stay in software development field.