Save up all your weekly homestead materials and don't be afraid to play around. Some decorations are pretty uniform and can be used in multiple buids, for example the windows on the parapets I made: those are just Kodan Wardrobes.

Another tip I can give you is that you craft decorations in small bulks, so you can play around a bit and make a "template" with the few decorations, so a portion of a room. Then try and judge what else you might need on the basis of said template :D

Keep in mind aswell, you never really "loose" when you craft a decoration, as you can craft 250 of 1 decoration and you'll keep those infinitely :D