All good firms have some Best Clients (the ones you would clone if you could). Great Firms have mostly Best Clients. Attracting more of your Best Clients is essential for becoming a Great Firm.
The challenge is knowing why your Best Clients choose you and will go nowhere else. Your Best Clients have the answers you need. You just need to learn to think like your clients.
My reverse engineering approach to marketing strategy answers this question.
The reasons you get selected have little to do with experience and credentials. Lots of firms do great work -- or at least they say they do. What attracts YOUR Best Clients to YOUR firm is the way you operate. Often, "little" things you do create big impacts in the eyes of your clients. If only you knew.