One way to leverage your stock market investment.
Use the shares you have bought as collateral for a loan so that you can buy more shares!
Depending on the lending ratio that the broker/bank allows you, you can buy a lot more shares for your initial investment. Say, for example, the ratio is 10% (like it was in 1929) -- you could buy $100,000 worth of shares with only $10,000 down! if the ratio was 50% (more or less what it is today) -- you could buy $20,000 worth of shares for $10,000
Naturally, this means your profits are magnified if the stock you buy goes up in price. The downside is also that losses are magnified as well and you may receive an infamous margin call if the value of your shares fall too much.
There is, of course, interest to be paid on the loan outstanding. This will depend on how much you have borrowed and the prevailing interest rates.