The power of referrals. Most people rely on word-of-mouth referrals. That means that they are being reactive and waiting for those referrals to roll in. Even though word of mouth referrals can be enough, you can always have more and more money. Referrals are the most powerful form of obtaining customers, because it is free.
My friends at New Velocity told me that 88% of people are willing to provide a referral, but only 8% of people ask for them. Make sure that you are on LinkedIn and have a well rounded, professional profile. You also want to share valuable content.
On LinkedIn, start looking at customers you have and who they are connected with. If they are a good client and they are happy, you can reach out to them and ask them to connect or introduce you to someone that may potentially be a customer. A good tip is offering to write up an intro letter for your connection to save them time. They will be more willing to help you out. You can even offer a bounty for any referrals.
Referrals are very powerful. Do not underestimate them.