DON’T: Let negativity become your go-to response. There’s nothing more draining than a boss or coworker who is constantly negative. I call these folks “energy drainers.” They are never happy, rarely supportive, and constantly nay-saying any and all ideas and suggestions that aren’t their own. According to them, you might as well give up before you start.
DO: Respond constructively when someone offers up an idea. Even if you know more about a particular project, have more experience than the rest of your team, or are positive that the suggestions others are making are off the mark, hear them out. Let employees and coworkers know that when they come to you with their ideas, they’ll be heard with an open mind and received with respect. Insist that everyone else practice positivity as well. While negativity squelches creativity and initiative, an encouraging attitude will keep creative juices flowing and encourage constructive dialogue.
As pessimism rises, performance decreases. You have to encourage optimism and guard against pessimism, or your team will suffer.
MEspecialist 
Great information. By doing these tips it makes it a safe enviroment for people to share Ideas.