Steel can be recycled easily and cheaply
Use steel sheet with recycled material content
Galvanised steel can be handled in the steel recycling process but avoid galvanised steel sheets with chromated coatings
Recognise that the smallest amount of copper and tin can disturb the recycling of steel (and aluminium).  It is very important that any components made of copper and tin can be easily removed by disassembly.  As little as 0.1% of these metals degrade steel scrap to be used only for specified casting qualities.