Think about your expectations related to involvement
With crowdsourcing you need to be willing to not micromanage. If you use crowdsourcing to involve others, then you need to embrace the input. If you limit the involvement of the group or do not value their contributions, then you stifle the group and you severely limit the potential of your ability to obtain valuable input from the group. Usually those involved in crowdsourcing are there to give valuable input and help develop a company or an idea. You need to empower them, and in doing so, you will reap the benefits of many minds contributing to your business.
Make your expectations about roles clear
If those involved in the crowdsourcing know your expectations about roles, then the input you receive will be more focused. Do you want creative ideas? Do you want practical ideas? Be very clear about what you want and then you will not be frustrated at not receiving the input you need.
Be clear about context
What is the vision and philosophy of your business? What is the culture of your business and the individuals you involve in your business? The individuals involved in crowdsourcing may not know your business and need the context. Give these individuals a foundation and they will spend less time understanding you and your business and more time on providing valuable input.
Combine these three best practices and you will find crowdsourcing more valuable to you and your business and you find you can empower those involved.