Making ideation productive
First, move from reactive innovation to proactive innovation. Many firms have open brainstorming or an open suggestion box. The outcomes of both of these approaches is great in the short term and fairly devastating in the long term. Open suggestion boxes will receive hundreds of ideas about a wide range of concepts that for the most part have little to do with the opportunities and challenges the firm faces. Rather than wait on ideas that individuals want to submit, the firm should become "proactive" and reach out to the employees for ideas on specific topics. Moving from a reactive stance where you receive any idea from any person, to a proactive stance, where the innovation team targets a specific problem or opportunity, means you may receive fewer ideas, but the ideas you'll get will be more specific and actionable.
Second, you should frame your opportunities or challenges. State specifically what Problem, Opportunity, Threat or Trend you want to address. This Problem, Opportunity, Trend or Threat framework is one we've developed and believe works well, but you may develop another framework. Again, this approach may reduce some of the volume of ideas, but will result in ideas that can be implemented and fit within the context of the needs.
Third, prepare your team. Many times brainstorming or ideation is seen as a short vacation from work - there's little preparation and most people know little will be done with the ideas once they are generated. Instead, send your participants pre-reading materials and homework. Help them arrive informed and aware of the key issues and challenges. Demonstrate how the best ideas will be assigned for further evaluation to demonstrate the ideas won't simply die in a file folder.
To use a food analogy, you wouldn't expect to be able to create a gourmet meal by selecting items at random from your grocery store aisle. Instead, you'd select a recipe, obtain the specific necessary ingredients and prepare the food as instructed. Every step in place and has it's purpose. Brainstorming and ideation follow the same logic.