Interaction with the designers is extremely important for the clients. Often, the business owners have many complaints to make when a designer submits the project. Too many improvements generally mean that the client did not make suggestions when the design was in its initial stages. When crowdsourcing your contest logo design, you need to be even more vigilant and offer your feedbacks in timely manner.
Crowdsourcing allows you access to dozens of design entries. So, you should be prepared to review dozens of logo design in response to the contest. One of the advantages of crowdsourcing is that you get many more design entries for review as against only 3-4 concepts offered by an individual professional hired. But you need to review many more design concepts.
You should be firm and final in making comments on the design entries that do not follow your contest logo design brief or are inferior in quality. You can say something strict with thank you mentioned in the feedback. Be respectful of their time devoted to your cause.
Pay more attention to the designers whose submissions you like the most. Give them feedback regularly whenever they submit the design with improvements. Encourage them to take time to create the design with the guidelines you provide them in your feedback. Quick response from your end will send a message that you are interested in the design, which in turn will help the designers in putting more efforts.
Make sure that your feedback to the designer is precise and to the point. The designers need your attention more than ever after they have submitted the entries. They wait for your suggestions for further improvements. How the final design will appear depends on your regular interaction with the designers who you think are doing a good job for your contest logo design.