Well the stuff I end up selling the most is the stuff that ends up gaining traction on social media, and you never really know which that will be, since like only 1/300 things I draw actually get notes on twitter (so if you have something go viral, always make sure to add a link in there where the print is sold) and fanart is usually what does it. (and surprisingly I get the most Redbubble sales from people who find me on Tumblr, which is weird) The nice thing about POD sites like Redbubble is that they have a variety of options--from prints, to cards, to t-shirts. I sell a whole bunch of stickers on there, although stickers are like...a 20 cent profit lol.
But youknow, just start drawing a bunch of stuff and putting it on there. Why not? If anything it makes you look more profesh to have a storefront.
As for pins, they're actually a really big investment. A lot of artists actually run kickstarters just so they make enough money to make the pins.