Throughout much of your working life, you contribute to your 401(k), IRA and other investment accounts to help ensure a comfortable retirement. However, once you do retire, you’ll need to shift your focus somewhat from building these investments to using them – in other words, you’ll have to start withdrawing from your portfolio to meet the costs of living. How can you be sure you’re not taking out so much that you risk outliving your resources?

First of all, you need to establish a proper withdrawal rate – the percentage of your portfolio’s value needed for one year’s worth o...