As okidoki mentioned above, we have a wiki with tons of curated resources. We even have example character meshes! http://wiki.polycount.com/wiki/BaseMesh And tons of example wireframes to examine and learn from http://wiki.polycount.com/wiki/BodyTopology http://wiki.polycount.com/wiki/Limb_Topology
To add to the advice above: Look at a set of assets and see what you can share between them. Your grocery store example has a lot of the same shelves and trim pieces that could be reused.