(Note: These tips may vary depending on the event and coaching style of the coach)
Coaches for these events should help teach their students about tips and techniques for using tools and various materials. The coach should demonstrate the skills on scrap material and then supervise the student’s practice attempts. Finally, it will be the student who performs the task upon the actual project workpiece.
The coach should not dictate a design to the student and then use the student as a technician to build the adult’s design.
Point out basic concepts using examples of every day life machines. (ex: gears, levers...)
You can find local experts almost anywhere. The local engineer down the street, the retired army officer may know a lot about trajectories. The helpful sales rep at Radio Shack may know of an inexpensive component that will just fit the bill. The local hobby shops also know of local rocketry and model airplane clubs who have people willing to help the newcomers.
Encourage students to try more than one design idea if time allows. Test each design and plan on rework and improvements. While a first attempt is perfectly acceptable as an entry, the best machines are usually the result of continuous tinkering and improvement. In very popular events, where many students are vying for a place on the first string team, break the group up into smaller teams with each team working on a different design idea. This builds some healthy competition and increases the overall learning of the team.