To start living the high life that much earlier, avoid these ten common mistakes rookie investors often make.

1. Not paying off debt before investing. Do the math. If you're paying 15-20 percent on credit card debt, and averaging only 10-12 percent annual return on your stocks, you're paying out more money in interest than you're earning on your investments. Call your credit card company and request a lower interest rate. If you can secure an interest rate below 10 or 12 percent, it makes sense to start investing - as long as you also make a plan to pay off your credit card debt.
2. Not knowing your goals. Are you saving for a car you'll need in a year, a house you plan to purchase in five years, or both? Make a list of your short and long-term goals, keeping in mind that, as a general rule, most investments double in value every five years.
3. Looking for bargain stocks that hit new lows. You get more for your money, right? Wrong. Most of the time, companies are cheap for a good reason.
4. Listening to someone about that 'hot tip.' Too many investors take a friend's advice because he or she always seems to know what's going on. Next time someone starts spouting hot tips, nod your head politely and feel free to tune out.
5. Timing the market. Waiting an extra day, week, or month to try and buy in at the "right price" just doesn't work. Successful investors use time and patience.
6. Not paying attention to transaction costs. You'll rack up high transaction costs if you trade frequently, which will cut into your gains.
7. Not selling poor investments. Don't hold on to an investment believing that it will "come back" or because you're emotionally attached. You give up the higher returns you could be earning by investing in a good, growing company.
8. Not selling profitable investments. Investors often become overconfident when a stock they own is doing well and think it will always deliver amazing returns. Always stay up-to-date on your investments.
9. Making panic sell decisions. Maybe an analyst downgrades the stock or a piece of bad news comes out in the media. Stay calm and make an educated decision. Assess whether it will affect the company long-term or if it's just a short-term blip.
10. Not reinvesting. Once you've made some gains, reinvest them by adding another company to your portfolio. If you pull your earnings out early, your money won't compound as quickly, leaving you with a smaller chunk of change down the line. Another easy way to reinvest is through a company's Dividend Reinvestment Plan (DRIP), which allows you to reinvest the dividends you earn back into the company's stock.