Have fun! Chat with other teams and peers :)
Develop the idea and be on the same page as a team before focusing on technical problems.
Brainstorm the full system before starting out on the details. Don't be afraid to revisit the full system after diving deeper into the details of subsystems and components.
Manage wires well and solder into permanence when possible. Removing the need to check whether wires are still connected reduces the time in debugging significantly, especially while integrating.
Leave room to prototype and iterate!