Find a great brokerage with excellent training.

Work open houses, get out of the office and meet people. Network and ask everyone you know and meet for business. Everyone is a prospect.

Get face to face with your circles of influence, add them to your database and ask for referrals.

Like Evelyn said, contact everyone you know.  But also start asking them if you can send them houses as practice from the MLS.  Many will let you and many will refer you to somone they know who is wanting to buy or sell.  The thing to do is to join a networking group and start blogging every day here at AR!

Make a list of family, friends & co-workers and mail them a nice card anoucing you are in Real Estate now.  Then call your SOI list asking for refers.  Good Luck!

Watch what the most sucessful agent in your office does , be honest in all your dealing,  ask a lot of question,  go around your neighborhood passing out your cards and meeting people. Hand out your cards everywhere you go. Return all calls as soon as possible.

Keep in mind that there are a lot of jerks in the housing industry, do not become one of them.

Get started writing lots of neighborhood blogs another blog post that will attract buyers and sellers

Be sure you get with an office with great training, mentorship and support. It isn't always the biggest company. 

Here is a link to one article about that: http://activerain.com/blogsview/35450/how-to-interview-the-broker-in-charge   

You can also search for other such articles on Active Rain.  Search box is at upper right of this page.

Host open house often.  If you don't have your own listings, ask colleagues if you can host open house at theirs.