Consider putting a 8 -12foot awning (extend the roof) out from the front. That way you will have 100+Sq.Ft. of semi protected area. Put the anvil about 3-4 feet outside the door, and cover it with a BBQ cover (it is too heavy to move in and out). Mount the post vise just outside the door ( you can cover it with a Weber grill cover). Put the forge on a rolling welding cart (HF - $49.00 ) and roll it wherever it is needed. Put the press on one side of the shed and put the bench (with the grinder and drill press) on the opposite side. Put any other power tools by the press (band saw, etc.) Put hooks, racks ,and storage on the back wall. The awning area is the best place to forge in, as it gives fresh air and even light ( and it will get hotter than H*!! in a 12X12 with the forge going ).You can put the 100# propane tank out side the door,too. My smithy is pretty much what I have described. There are BBQ covers over all kinds of equipment that I don't have room to store in the two small enclosed buildings (anvils,post vise,bench vise,big band saw, caulking vise,propane tank,12" pedestal buffer, etc.). The NC Lowboy forge is mounted on a swing arm and stays covered with a....you guessed it....BBQ grill cover (they come in almost any size imaginable) . The two buildings are 8X12 and 8X7, I use one for storage and one for the grinding shop. You can even make temporary winter side walls for when the weather is too bitter to stand out in the open. Anything you can mount on a rolling cart will be a plus (HF is your friend !!)
Hope this helps - Stacy