What other bikini bottoms do you already own to mix and match with?
I think a simple stripe or polka dot patterned bottom could go well with the top you own.
Just yesterday, I was looking at this picture gallery of Taylor Swift's "bikini style" on one of those celebrity gossip websites. I loved the type of bikini bottoms she wears, they're high waisted and cover your belly button, which I think look so classic pretty and cute! Reminds me of Rachel McAdam's swimsuit in The Notebook.
It's also a way to cover up a bit more if you want to.
I don't have enough posts to share links yet... But I found this picture of Tay Swift and I thought the way she mixed her bikini top and shorts that are different colors/patterns looks really great! Try googling "taylor swift bikini", it's a few rows down, she mixes her red polka dot bikini top with some diagonal black/white stripe shorts.