Since you already know how to use GDB and you're familiar with Assembly, Now i don't know how much Assembly you know, but you need to know how programs execute

Since you already know how to use GDB and you're familiar with Assembly, Now i don't know how much Assembly you know, but you need to know how programs execute in memory, (stack , heap , syscalls.....), and once you have that clear in your mind, try to draw a map of thoughts about the logic of execution of this binary (it will be pretty simple, since it's generally small programs), look for the points and weaknesses in the logic that you might attack, one tool i use frequently is [0]peda, also using some visual gdb extension would be really helpful for you instead of checking and looking every time on how registers change values, sometimes a little knowledge about how compilers work and the OS you're working on will be really helpful although the binaries are independent in most cases, but extra knowledge is always useful. [0]https://github.com/longld/peda https://github.com/longld/peda