It's extremely important to speak your mind in the professional world. Expressing yourself openly makes you appear more confident, demands the respect of the people around you, and helps to illuminate problems before they grow even worse.
Whether you're bringing a complaint about working conditions up to a superior or criticizing a traditional marketing approach that needs to be changed, voicing your concerns is important--but it's also nerve-wracking. It's easy for your honest expression of apprehension to be taken as a negative complaint, forging a fine line between "problem solver" and "whiner." Fortunately, most bosses and supervisors will naturally favor the former impression, as honest feedback is necessary for a smooth operation, but if you're worried about how you'll come off, you can use these strategies to soften the blow.
Time Your Concerns Appropriately
Your first goal should be to bring up your concerns in an appropriate manner. If you're in the middle of a staff meeting and you don't agree with a new policy change, blurting out your problems with it during the meeting itself is a bad idea. You also don't want to complain about something trivial--like a coworker's behavior--during a time of crisis in the office. Instead, schedule some time with your boss for a one-on-one meeting in private, and make sure it's still a good time before opening the discussion. This will set the stage for a much more productive conversation.
If you have concerns about something, be specific about it. Coming to your boss with a general complaint like "the atmosphere around here sucks" or "this whole marketing department can't do anything right" could ruin your reputation and instantly discredit your complaint. Instead, cite specific instances or specific fault points that you need to address, and the more specific you can get here, the better. Now isn't the time to mince words with generalities or ambiguities. Don't be afraid to name names and dig into details; as long as you do so respectfully, it will help your case.
Be Objective, and Lose Your Emotional Attachments
You need to be objective about your concerns, and that means losing your emotional attachments to the cause. If you're angry about the way management handled something, lose that anger. Focus on the facts, and come to your boss with a solid reasoning for why the problem needs to be addressed. For example, let's say your coworker scrapped your work in favor of his own and the project didn't turn out as well as either one of you had hoped. Instead of expressing your anger and frustration at the situation, state the objective costs of having an employee who refuses to listen to others, and recommend preventative actions to ensure the scenario doesn't unfold again.
Come With Solutions in Mind
It isn't enough to come to your boss with a problem. Doing so will make you seem like a complainer. Instead, come to your boss with a problem and a solution already in mind--preferably multiple possible solutions. If you do so, it will show that you've thought the problem through and you're looking at the future, rather than the past or present. Coming with solutions will also increase the likelihood that your boss will take action on your concerns--it gives him/her something to work with.
Focus on the Positives
Don't take up the entire meeting time talking about what's bothering you; instead, take some time to point out complementary positives. Doing so softens the blow of the criticism and also shows that you are aware of both the positives and negatives of the given situation. For example, you could say, "While Mary is a punctual and diligent worker, her work on these analytics reports is making it difficult to do my job," or "Our sales team has done a great job this year, but because we don't have a great follow-through process, I feel that we're losing some of our potential."
Leave the Decision Up to the Boss
Don't ever demand that a specific action be taken, or worse, introduce an ultimatum. Saying that you'll leave or take negative actions if your desires aren't met is a way of holding your boss hostage, which looks very poorly on you. Instead, frame your concerns as a request rather than a demand, and allow your boss to make the final decision with respect. Then, respect the final decision that is made. Even if you don't get what you want, at least your complaint will be on the record.
Get Support If Necessary
If a problem is recurring, or if your concerns have not been met with recognition, don't be afraid to get support. Assuming the problem affects more than just you, ask your coworkers to voice their complaints in a similar manner. Doing so will illuminate the fact that multiple people are affected by the problem, and will motivate management to take further action. In extreme cases, you can go above your boss's head, but only after repeated attempts to solve the problem at a ground level.
Use these techniques to make sure your concerns are voiced--and heard--without seeming like a Negative Nancy. As long as you focus on solutions, rather than the problem itself, and share your feedback honestly and calmly, you have nothing to worry about. If anything, your supervisor will thank you for bringing it up in the first place. It's impossible to make progress until someone addresses the problem.