3.7v to 3.3v voltage regulator
A battery's voltage sags as it discharges and the LiPo type is no exception. A 3.7V LiPo battery falls to about 3.0V when fully discharged. You will want your project to continue operating over the full range of battery charge state so you might want to consider a buck-boost converter that can operate with an input voltage down to 3.0V to get maximum run-time for your project.

On ebay, there are power supply modules that use the TI TPS63020 buck-boost IC. I see one for about $10 that should meet your needs. This solution is also more efficient than an LDO so you'll get longer run-time. Good Luck!