Different parts of the map:
Fire destroys forests and civilization. You can block its spread by keeping fire-blocking areas within your town. Water, towers, walls, canals, and clear land blocks the spread of fire.
Volcanos produce lava that flows downhill and fills up valley floors. Lava destroys everything in its path, and sets anything nearby on fire.
Blob soldiers are the basic military unit.
The lower altitudes are better for farming, but are more prone to flooding. Blobs prefer to live here, but can live anywhere.
Farms can survive in these higher areas, but do not produce as much food unless near a good source of water.
It is hard to grow food in the highest areas due to the lack of water, but a good canal system can help. Consider placing a military base on top of a mountain. Soldiers can travel faster downhill than uphill, so it is easier for them to reach an invading army if they are on top of a hill.