The best approach is to plug the extender in somewhere close to the dead zone you're trying to fix, but not within that dead zone. That's because you need the extender to have a decent connection with your router in order to put out a worthwhile signal of its own. To find a good spot, grab your phone or laptop, connect to your home network, and run some internet speed tests in various spots that are adjacent to the dead zone in question. Once you've found a spot near the dead zone that still hits usable upload and download speeds (preferably at least 50% of whatever you're able to hit up close to the router), then you're probably in a good location.