Simply put, If under 18, I'd instruct the student to persuade his parents to start a LLC, Trust, or Corporation. Analyzing what would be profitable and locating passion projects within the venture.
I'd show the student how easy building business credit is when you have a business and how much leverage you receive financially by doing so. In 45 days one could go from $0-$100,000 in business credit. That's far more powerful than anything else I can think of. There's more but that's a start.