the end of the road) then only use 1 section of road so that it only contacts 1 grid of the building because that's all you need - The fewer turns and corners you build, the more efficient the road design. Put large buildings like Barracks or wonders at the end of the road - If you're not using the 3rd side of the road, (i.e. Don't worry, sometimes you can't avoid it. This is common when people put cornered roads around buildings. If it has more than 1 side touching, then you are wasting road.

Roads have 3 sides, so put buildings on all 3! - Any building should have no more than 1 side touching a road.