Below is a list of ways that you can earn more free gems or credits.

Sign up for Tapjoy: 21 Gems.
Like Samsung on Facebook: 7 Gems.
Become a fan of Tavern Quest on Facebook: 2 Gems.
Become a fan of Glu Mobile on Facebook: 2 Gems.
24 Hour Fitness Free Seven Day Pass: 21 Gems.
Watch video for Tiny Zoo Friends: 1 Gem.
Get the Discover More Card: 873 Gems.

Some Cost Money:
Sign up for Netflix: 364 Gems.
Save 60 percent on Men's Health Magazine: 291 Gems.
Buy Flowers, Plants & Gifts from $19.99: 247 Gems.