Landscapes

This is one of the most comprehensive workflow Tutorials for Landscapes in blender.  He talks about how to blend textures, use meshes instead of displacement, and using lattice for randomness.   If you watch this video 3 times, first take the info in.  Second, take notes, third, Try different parts using his Add on. (free version)

Beginner

Intermediate

This tutorial shows how to make your landscape look more natural.  He creates masks for the factors of mixshaders that define the near, mid, and far areas.   Then he changes the scale of the texture he is using for the ground.  He also shows how to use a masks for the mountains.