Best advice is browse through male catalogs featuring guys your own age, to give you an idea what they're wearing: school, play, work. EXPRESS is a good male catalog example.
Browse through male fashion magazines, also. Models on a mannequin, in store displays are a good example. Check them out, what looks good on them, find the color of their hair & complexion to match yours. If they look good in that outfit, it's 90% will look good on YOU.
First of all, clothes has to be comfortable, and gives you enough confidence. You're 17, don't know how much you can afford, but you can pretty much spend $300 on one single outfit for the day. Try to be frugal, mix & match is the key, not the latest & the best. Buy your favorite colors, they will match the bottom no matter what you wear, and mix with whatever else you want to add. If you've got dark hair, dark bottom works best, then add a lighter shirt to balance.
I also suggest when paying for online purchases, don't use Paypal, it takes just once to be a victim. I was and it took 3 years to get my credit. Use your Credit Card, always, they can help you if any disputes.
AND beware of international shipping, they could add 3-25% extra fees, even if the price is cheap.
My merchant was from Texas, but the product was shipped from Hong Kong.
Other times, when you need to call Customer Service, they speak in foreign tongue and no one to translate them or JUST they don't answer calls.
Buying husband's clothes for 38 years, 2 sons, 40 males cousins.