As an expat you know that everywhere you live your house is different. This means a high turnover in furniture&accessories. Buying stuff that suits your current house & lifestyle, but also selling stuff so you don't stock up too much before your next move.
There's the Russian marketplace "Avito" if you want to practice your Russian but if you prefer a more low barrier marketplace, try Moscow Expat Flea market on Facebook with almost 8000 members. Just request for membership and you can post and "buy" your stuff in a heartbeat.
Photo credits: Facebook page Moscow Expat Flea market