Build relationship with clients who pin often, they are the ones with the most followers. (more chances for you to get repined). Ignore the others, your time is too precious to waste on following smaller Pinners.
Cross pollinate your social media. The other social media sites have vastly more users than Pinterest. Use your other social accounts to direct to Pinterest.
Of course pin your products, but also pin about things and stories related to your industry. Tips and tricks related to items you sell make it more human and less about the sales.
Getting clients and potential clients to follow you on Pinterest is important, but just as important is for you to follow those “super” Piners. They may follow you in return giving you that all sought after social media exposure that costs almost nothing to buy!!