Having a good definition of who you serve is the perfect place to start.

Could you define it further..? Do you specialise..?
Really drill down.

How to find those people?
One of the quickest low/no cost ways to find your target audience would be to use LinkedIn.

You have access to a database of C level decision makers & most of the time direct access to them.

Join industry related groups - posting samples of what you do to generate inbound enquiries.
Post calls to action in each example to enquire about your services

Once your a member of relevant groups you can also use the search functions to find those perfect customers and proactively connect with them.

Doing this the right way is a whole course in and of itself. Just know that through linkedIn you can connect and connect any and all of your perfect customers worldwide.

Good luck
Phil