One thing you need to be careful of is thinking of the 401K plan as a savings account, as I think many people can fall into the trap of doing (let's face it, when you work in this industry and live paycheck to paycheck thinking in terms of the long haul financially can be difficult to do).
It's a retirement investment tool and you need to make sure that when you make a contribution that you are willing to forget you ever had that money for the next 20 or 30 years, depending on how far out from retirement age you may be. The penalties for early withdrawl are enormous and just not worth it. So if you think you might end up needing the money in the near future, DO NOT put it into a 401-K.
Also, if there's no matching contribution, and you have credit card debt it makes little sense to contribute until your debt is paid down. The interest you're paying on that debt most likely far exceeds any potential returns on your investment. If you have debt and you're putting money into a savings account or retirement plan, odds are you're really not saving money at all. Use the money you have saved to pay off your debt and THEN start saving (unless it's already in a 401-K--again those penalties!!). Of course, I always try to have a cushion to get me from gig to gig, but in the long term scenario paying down debt is step #1 and should be an absolute priority.
The exception to that rule is if there is an employer contribution (for those with "real jobs"). In that case, even with debt, you should contribute because that employer contribution is free money. In other words if your employer contributes fifty cents for every dollar that's an automatic fifty percent return on your money and you just can't pass that up. So in that case you would contribute up unitl the limit that your employer matches and then stop contributing and then turn your attention back to reducing debt.
Also consider a ROTH IRA. Unlike a traditional IRA, you do not get the tax deferral because it's paid with after-tax money, but you may withdraw your contributions at any time without any penalties. Only the earnings on your investment are subject to taxes and penalties. In other words, If you invest $4000 and that money earns $200 in a year, you can withdraw the $4000 without paying a dime. However, the $200 in earnings would be subject to income tax and the penalty (which I think is 10%, but that number could be wrong).
There's a great book out there that has been extraordinarily helpful to me--"The Money Book for the Young, Fabulous & Broke" by Suze Orman. Pick it up!! This woman has changed my life. She manages to make financial planning seem manageable and concrete, not just some abstract numbers on a page.