Tip - Should I Put Money into My Employer's 401(k) or Invest on My Own?

Dear Lifehacker, I want to put a little something away for the future, but I've heard a lot of people say that maybe my company's 401(k) isn't the place to keep my money. Should I invest on my own, or stick with what my employer offers? Should I do both? How can I tell if my 401(k) is good or bad?
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