Run towards conflict
One behavior I keep running into with most newly-formed teams is the overwhelming desire to steer clear of any conflict. This is very apparent when the team is brainstorming different ways to work, setting up processes, or even worse: drafting a roadmap.
This is a problem, because your initial conversations set the stage for the pattern of your conversations in the longer term. If you can't find a way to handle disagreements when you're starting out, it's only going to get so much harder later on (a fear of conflict is also one of the signs of a dysfunctional team).
If you're part of a new team, invest more time up front identifying your differences and how best to leverage them together, and less time reaching for consensus. It's worth it.