You will never get your first client sitting in front of your laptop. Few things you can do is - Build a free site for a small business in your neighbourhood. Go out and talk to them. Build it like you are building your own. Then slowly word-of-mouth publicity will start getting you clients.

If you are planning to register on websites like oDesk, then i would suggest you to work under someone who is already there and have a client base. Then slowly start building your own.

I hope this will help you. Good Luck!!