Realm of Chaos has a tutorial on basing using techniques I gleaned from back in the 1980s when I first started playing Warhammer Fantasy.
modeling
Making Sandbag Barricades and Bunkers
Here’s a useful video tutorial on making sandbag barricades and bunkers.
Modeling A Dark Ages / Medieval Village
Battle Brush Studios has a tutorial on making a dark ages / medieval village.
Modeling A Bombed Out Building
Here’s a tutorial / demonstration on making a nice looking bombed out building.
Modeling Dirt Roads, Tracks and Paths
Here’s a nice instructional video on modeling dirt roads, paths and tracks for your wargames table.