I think with $300 i will prefer on Bitcoin-altcoin trading, beside we can use small capital on it, usually exchanges that allow trade between bitcoin and altcoin not really strict and maybe KYC will only to increase limit withdrawal. And in altcoin trading, you can see movement price that you can put what is fit with your style. Like to day trading or maybe long term investment. That is at least what i will do with my $300 free money. And if lose, i will pick on full time job. Wouldn't dare to left my job and focus on trading only because we can't know when trading will on bad condition.