External suppliers are critical to the success of nearly every business. Some vendors become trusted partners, while others have good intentions but struggle to deliver. A few fail so miserably they never get a second chance.

Over the past 20 years, my marketing agency has hired dozens of creative and production vendors. We’ve seen the good, the bad and the ugly, and we’ve gained some valuable insights into what makes a great client-vendor relationship.

Here are 10 tips to become your client’s favorite vendor:

  1. Share ideas and knowledge. Clients welcome suppliers who can offer ideas, knowledge and experience that will produce a better outcome.
  2. Ask questions. The best vendors ask smart, insightful questions to fully understand the client’s needs. If you’re not sure what the client is asking for, don’t make assumptions. And if you can think of a better way to do the job, speak up.
  3. Be honest about your capabilities. A printer once assured us they had in-depth expertise in Personalized URLs (PURLS) for a direct-marketing campaign but couldn’t produce any samples. If you aren’t 100 percent sure you can do the work, be upfront about it. You and your client will both be sorry if you fail.
  4. Deliver excellence. It seems obvious, but suppliers should take every step to deliver a high-quality product. No one’s perfect, but when a vendor falls short on quality control, the client suffers the consequences.
  5. Be consistent. Sometimes a supplier produces outstanding work for one job and mediocre results for another. Businesses need vendors they can count on; no one should have to worry the supplier might not come through this time.
  6. Meet deadlines. The supplier’s promises about delivery impact the promises others make, internally and externally. When you make a commitment to a client, keep it.
  7. Communicate. Always keep your clients posted on your progress, especially if you’ve having issues or need information.
  8. Don’t surprise a client on an invoice. If the scope of work changes and extra charges will be required, tell the client right away, before the costs are incurred. Don’t wait until the invoice to deliver the news.
  9. Say thank you. Always thank a client for giving you a chance to be part of his or her team.
  10. Look for opportunities to refer a client. We’ve had several new business leads from marketing vendors who’ve referred us to their clients. This isn’t expected, but it’s always appreciated.

When a company gives you an opportunity to become a supplier, follow the best practices of business—responsiveness, dependability, honesty, quality and creativity—to build strong relationships and become a preferred vendor.

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Jean M. Gianfagna is a marketing strategy expert and the founder and president of Gianfagna Strategic Marketing which provides marketing strategy and creative services to leading business-to-business and consumer marketers. Read her blog for more marketing tips at http://www.gianfagnamarketing.com/blog.