I never built a lot of terrain for my games... Most times I use the tables of friends because my terrain building skills are really not that evolved...
So far I only painted some of the plastic ruins from the LotR Starter Boxes and built the cardboard houses from the 5th Edition Warhammer Starter Set which I found again last week, when clearing out the lumber room.
Forunately I found this article from graphixx at the German LotR forums. graphixx uses a simple but effective way of modifying cardboard models into great looking pieces of terrain.
I tried this method with the old houses and it proofed to be an ideal way even for terrain-no-skillers like me...
First, I worked on the shed. I simply glued some stripes of balsa wood to the walls. The printed surface of the paper model already tells you, how to do it.
For the broken door I added some hinges cut from plastic card.
Done...