Order of investment options
Investment options (from best to "worst"):
401(k) ----> IRA (Roth or Traditional) ---> Taxable account (i.e. non-retirement)
Even if your employer isn't matching your 401(k) contributions, remember that it does reduce your taxable income since the contributions come out of your pre-tax income, and you will end up paying less taxes. For instance, if you make $1,000 per month before taxes and contribute about 20%, your taxable income will come down to about $800. If the tax rate was, say, 30%, you end up paying $240 in taxes, versus $300 (i.e. 30% x $1,000) you would have paid had you not contributed to your 401(k). If your employer did match, however, it would have been a sweet deal, since it's virtually free money.
That said, even if you are maxing out your 401(k) contributions, contribute what you can to an IRA. If you maxed out on your IRA contribution and can afford to save even more, make sure you put that into a mutual fund account too.
One last thing: Don't just mindlessly allocate your 401(k) contributions. A lot of Americans make the mistake of dividing their contributions equally to the funds offered in their 401(k) plans without a thought of how asset allocation (i.e. how much bonds, stocks, real estate, etc. in you hold) can affect their returns. As Vanguard founder John Bogle once pointed out, asset allocation is the second most important consideration when choosing what mutual funds to invest, right after expenses.
I hope this helps. Please feel free to ask me more questions.