Amazon has always attacked this problem by trying to have the lowest prices. They were also the first major retailer to provide sophisticated recommendations, which helped people make the right decision the first time.
And, more recently, they have tried to drive the cost of shipping and returns as close to zero as possible.
All of those are good strategies, but recommendations are tough for furniture and free shipping/returns are probably impossible. If you want to succeed, you'll have to figure out your own method of eliminating fear and buyer's remorse.
If your furniture is available in show rooms, an app/website that helps people see the piece in person and then buy from you would be great, e.g. "See this piece at [insert address here] between 9am and 5pm today"
If it's not available in show rooms... I don't have any other ideas.
Edit: another strong recommendation: NO fake/CGI product photos! Those are a screaming red flag to consumers. No one in their right mind would buy a $3k couch with a photoshopped product image.