Eyes glaze over at the words "soft skills" for developers of both the "ship it" and technical purists camp. Unfortunately, humans aren't emotionally empty robots and team work is generally required to build anything of sufficient complexity. Trust helps build innovative and productive teams. Trust is built up from cultivating safety and vulnerability and we can achieve these characteristics through effective communication.
Listening comes first. People trust when they feel heard. Listening takes patience and being patience is a skill that takes effort to improve. When we listen, we can bubble with questions, agreements, and disagreements. Disagreements may cause us to stop listening. Especially disruptive are disagreements about expressed emotions. This is when respect comes into the picture.
Respectful listening means emotional validation. Although you may not think that the other party's emotions are real that does not change the fact that the other party feels them. It is disrespectful to hold the stance that you know a person's feelings better than themselves. Validating someone else's emotions means you trust the other party. A lack of trust tends to form from the worry that other people are manipulating us. To properly validate other people's emotions we need to take the leap of faith that the other party is being honest with us. People look at others who share as having great depths of courage to draw from, but it is the act of sharing that creates courage. It's the same with trust; in order to trust others we also need to foster trust. I won't deny that there are situations where someone may be manipulative and if you find you are surrounded by this type of behaviour, get out! Signs of manipulation tend to be oversharing of information (the subtle approach) or out-shouting peers (the less subtle approach).
A conversation has two directions. We can weaken our discourse by being aggressive or not even participating at all. When we don't participate that's known as submissive or passive communication. Both passive and aggressive communication can erode relationships. Refraining from sharing information does not encourage others to share. Aggressively attacking shared information creates cold speech. People fall into the aggressive mode of communication by likening it to boldness and assuming that effective communication is bold communication. Those with aggressive communication then cause others to refrain from sharing.
Assertive communication is middle ground. Instead of chipping away at a collective sense of safety and willingness to share, it helps strengthen relationships. From a time management perspective it may make sense to say "no" to as many things as possible; your time is a precious resource and wasting it with needless tasks is a waste. But we don't always have to frame a "no" with the word "no". One variation of this technique I've found incredibly helpful is the "yes and ..." approach. When you say "yes but ..." you inadvertently invite debate, but when you say "yes and ..." you validate the other person's option and provide your thoughts in addition.
Assertive communication is also respectful. As such, avoid using accusatory language. Often when we feel something there is a tendency to state an accusation rather than a reflection of how we feel, such as "I feel nervous about this option" as opposed to "you are always trying picking lousy options". Note, also, the use of the word "always". Using exaggerated language tends to intensify debate. How do you tell someone they need to switch gears after a lot of wasted effort on irrelevant details? Reminding someone of the facts will have a far greater impact that the ensuing isolation created from making a judgement on the person's ability to act.
Also, speaking with intent tends to encourage healthy discussion without stopping healthy activity. This is one of the most empowering things I can recommend. Stating "I intend to ..." allows others to raise any concerns but also makes it clear that this is something you truly are going to do unless there are serious complications with it. Paradoxically, asking for permission tends to foster a lack of action and discussion.
Lastly, things that may seem useless but have big impact are making eye contact (you can even possibly get away with looking in the general area), posture, and smiling. And that's it, really. Validate, share, be intentional, don't be an asshole even if you're technically right, and you will go far in developing trusting and cohesive teams than if you plugged your ears and pretend everything comes down to luck.