Make a list of these categories.

Active clients Inactive clients Special buying category clients Frequent purchasing clients Larger average purchase clients Special industry based clients Independent sales and distributors Professionals Industry trade contacts Key suppliers Non-competitive businesses in your field (not competing directly with you) Businesses that sell key products or services that complement, parallel, amplify, follow or combine with the product or services you sell Key executives above or under you Key influential people you know Add more as you think of appropriate categories