iPhone 5 memory problem

I recently bought an black iPhone 5 16gb and installed some games to play. Then my iPhone warned me that i am low in memory. So i tried to delete some apps and check my usage but still no change. So i restored my iPhone and install some of the games and i had the same warning again. i only installed like 12 apps and they prom me that my iPhone is low in memory. Does anyone have a solution to this ?