There are pros and cons to both. It is certainly easier to find someone online. Websites such as this one allow you to hop right into a pool of fellow kinksters, as oppposed to the good ol' fashioned approach of finding a local munch group or wandering into a club and hoping you Dom-dar is working. If you are cautious or perhaps intimidated a little, online also offers a nice buffer behind which to get to know a person at your own pace. On the other hand, if real life interaction is your goal then you have to realize that a person you have good chemistry with over the computer may completely fail to flip your switch in the flesh. Perhaps you'd rather know that sooner rather than after a good few months of time comsuming emails an online tasking.

Whatever you do, I do recommend reasearching and learning all you can before you jump into anything, online or real life. Talk to lots of Doms, talk to lots of subs, and let yourself learn the Lifestyle from the group and establish your own perspective before you let any one single person be your guide and your insight into BDSM.

Best of luck.