I suggest you build a few "apps" which are highly focussed in what they do but are more-or-less feature complete and publish it on GitHub. This works better in some areas of software dev than others, but it will basically demonstrate that you can ship a product in an area that you have expertise in. As a contractor, your ability to ship code is the most important point of evaluation for people trying to hire you. With the source code available, people can also validate that you can write decent code. Having such a showcasable portfolio of work will definitely put you in the top of the pecking order.