Have fun! Chat with other teams and peers :)
It is about the journey and the learning.
Get a watercraft going in the water ASAP.
Develop the idea and be on the same page as a team before focusing on technical problems.
“If a man knows not to which port he sails, no wind is favorable.” ― Seneca
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.
Work on the Communications Protocol early! Having it done will streamline the testing process when you have a water-ready boat and assembled controller.
Test your controller with other teams' boats and your boat with other teams' controllers (as early and many as possible). There will probably be something in the communications protocol that will need to be iterated on.
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!
Concurrently work through mechanical design and software development. Issues in software may lead to changes in mechanical design and vice versa!
Simple is better. Having fewer parts leads to simpler mechanisms and systems that are easier to design, build, and have fewer failure points. Don't underestimate the need for reliability.
Test early, test often, and test extensively.
Test progressively. Design for yourself cascaded milestones as for too much at once will delay reaching milestones.
Build modularity and adjustability into the design. Full disassembly takes time, so design parts to be swappable with minimum interference from other parts.