Don't buy penny stocks. At your age don't buy stocks at all. Even seasoned buyers get taken way to much and sucked in and chewed up. Your emotions will run high and you'll make bad decisions until all your money is gone. Seriously don't do it. Some day when you have more money you can throw away you can start learning slowly until you get the hang of it. Maybe if you really want to get in on something buy some beaten up oil stocks and hang on for like very long term.
At your age though, being so young and having a ton of time left in your life you just want to be building wealth. Normally if interest rates weren't so low that would include just throwing it in a high yield savings account. And keep adding to it and watching it grow. But interest rates are horrid these days. And since you're on precious metals forum, don't have enough money to diversify anyway, and have decades to hold and build up wealth, I'd say just stick to buying silver.. Wish I did at your age.
Your silver will be something you shouldn't touch or sell for decades. Geez even in 30 years you'll only be 43. Imagine silver in 30 years and how much harder to get and rare it will be. Will be insanely expensive. And you'll get to hold it and admire it in the mean time. Maybe sell some to buy a house or something. Starting so soon by the time you get out of college you'll be so far ahead of anyone else it won't be funny.