Pairing an overcoat with a grey crew-neck sweater is a good choice for a casually neat look. For something more on the daring side to complement this ensemble, introduce grey athletic shoes to the mix. Semi-formal looks for stylish teen guys aren't actually that hard.
This combo of an overcoat and a grey crew-neck sweater looks classy, but in a modern way. Clueless about how to round off? Add a pair of charcoal canvas high top sneakers to the mix for a more laid-back feel. If you're an adolescent, take inspiration from combos like this to add more maturity to your look.