Your Hatcheries are your recruitment stations. Therefore they are comparatively more useless than other Resource or Defensive buildings.
Most people build their Hatcheries all the way outside, using them as part of a NEC. That is certainly the best way to go, but try to position your Hatcheries at the south side or south-east side of your Yard. The tall Hatcheries shield UNfortified towers from view, making it quite a shock for your enemies when they discover that there actually WAS an ADT in your Yard.The Hatchery is one of the most important building , so it is advised to protect this building .
Fill up all your Hatcheries with monsters. Once the Hatcheries are knocked down, the queued monsters will die and your Goo is returned to the Silos. Your NEC (Hatcheries included) should delay enemies long enough to prevent your Silos from being breached.
If your enemies attack your Silos first, after you have used up your Goo to make monsters, they will get a pathetic amount of Goo back, and if they then kill your Hatcheries, they can't redestroy your Silos to get more Goo.