First, you need to find your target Business Niche.
Second, Use google maps to find businesses under those niche. Maps give you information about the business.
Third. Check out their website, If you are looking for designing their website. Thoroughly point out UXUI improvements that can be done to increase their ROIs. If you are looking for graphic design, check out their social media pages. Check out their designs. You can provide some sample designs better than what they have been using. Mail your concepts to the client. Also publish those designs in Behance, Dribble, Instagram as fan artworks. Use their business tags. You will some how be noticed one way or the other. Hope this idea helps :)