While I'm certainly no expert, I can give you the basics. First off, you would need to diversify your investments. Investing $300 in one company is risky, although the amount of money isn't a lot. Try to find 4-5 companies you would like to make a medium term investment in, and spread your investments over these companies. Then I would start saving money monthly and placing them evenly into these stocks. That way you get the habit of saving money, at the same time as you spread your risk and gain the money from stock prices going up. If one of the stocks goes down, hopefully it will be covered by the rising value of the rest of your portfolio.
This.
Also, needless to say, make sure that the bulk of your investment goes to stocks that have the best tax-advantage for you. Certain instruments end up causing double taxation.
On the other hand, in the US, you could open up a Roth IRA and then invest in an index fund within the Roth IRA, and get the maximum tax-advantage that way.
Make sure to choose a no-load index fund. Thus, if your broker is fidelty, the index fund that will typically have no added fees will be one run by fidelty themselves.
- einbit.