There are two key things about mutual funds: what they contain, and how much they charge you in annual expenses (the "expense ratio"). Your early investment goal should be matching the market. An index fund that matches the market beats a majority of active funds each year, and 80%+ of active funds over 3-5 year time frames. It's simply too hard to predict exactly what one company will do, let alone 10 or 100 companies. Reading about it could be some of the most valuable reading you'll do if it improves your retirement results.
Second key thing is expense ratios. It's hard to predict which fund will do best next year, but an expense ratio predicts something very precisely: how much of your money will be used up by the fund. Low expense ratio funds tend to outperform high expense ratio funds. If they held the same stocks, the lower cost fund lets you keep more of your money. (It doesn't hurt they also tend to be index funds, which don't try to outguess the market's prices and weights).
I'll end with a message from the U.S. Securities and Exchange Commission (SEC):
https://www.sec.gov/answers/mperf.htm"This year's top-performing mutual funds aren't necessarily going to be next year's best performers. It’s not uncommon for a fund to have better-than-average performance one year and mediocre or below-average performance the following year. That's why the SEC requires funds to tell investors that a fund's past performance does not necessarily predict future results. You can learn what factors to consider before investing in a mutual fund by reading Mutual Fund Investing: Look at More Than a Mutual Fund's Past Performance."
https://www.sec.gov/answers/mperf.htm