One of the greatest tips and pieces of advice offered to individuals who are looking to maximize their 401K plans is to invest in mutual funds. There are a lot of companies out in the world today who will offer you the option of being able to invest in mutual funds as part of your 401K. This is a great option and is the key to smart investing. It’s recommended that you don’t stop with just your own company’s funds, but that you should diversify your investments with other funds.