I've had no experience in "RedBubble" nor do I know what it is. However I can advise you on Flickr. I am a Flickr pro user and I love it! It's a great service that allows you to add your photos to unlimited appropriate groups for others to see. Views are few when you first start, but I've been on since August 2010 and have 200 regular views. For Flickr, that's a decent amount. If you pay for a Flickr Pro account, you can view the stats for your account - where people are viewing your photos and why. It's a great service for building a portfolio of work and because it's so well known, you can't lose.
I'll wrap this up here before I start sounding like a Flickr employee. But I'd definitely say give Flickr a go. Very rewarding.