If you find yourself running short on time - say, you're in your 40s or even your 50s, and you haven't gotten started yet - there are still a few things you can do. The key is to do them now.
You should first max out your contributions to tax-favored retirement accounts like IRAs and 401(k)s. For 2012, the IRS allows $17,000 for a 401(k) (though your employer may impose lower limits), and $5,000 for traditional and Roth IRAs. If you're over 50, you can contribute additional catch-up contributions. Even the government understands that this is crunch time, and it has devised a few ways to help you out.
For example, workers age 50 and older can put more money into IRAs and workplace retirement plans than younger savers can. That means you can and should contribute an additional $5,500 to a 401(k) and $1,000 to traditional and Roth IRAs.
If you're arriving late to retirement planning, a traditional IRA may be a better choice than a Roth.