Review the fund's expenses Each year, the fund takes a percentage of the fund to cover the administrative and trading costs. It's important for you to review the fund's expense ratio. However, some aggressive funds charge a higher expense ration, but they also yield higher returns. In this case, a fund with a higher expense ratio would have to outperform the fund with the lower expense. If high expense ratios charged by actively managed funds annoy you, you can always buy index funds as a core part of your portfolio.
Most investors ignore tax planning when choosing their mutual funds.
For example, stocks with steady long-term goals tend to have better tax efficiency than aggressive growth funds. Some funds are reporting after-tax returns, but you can also check the fund's tax efficiency by reviewing its prospectus. A fund is only as good as the people managing it. Just like there exists both bad and all-star football players, the same applies to portfolio managers. Some people might argue that portfolio managers tend to be luckier than anybody else, which is why I recommend that you check the manager's track record.