For my business, it has been networking.  Since I am really selling "myself", no health insurance, building trusted relationships with referral partners has been the key.This can be more work...sometimes I attend  2-3 meetings or events per day.  It has also required a financial investment joining Chambers of Commerce or networking groups but people see that you are serious and passionate about what you do, they want to do business with you and refer clients to you.  The word will spread.  In two years my business is now 90% referral based.