[Tom Bottiglieri]

I choose something like this:

Variables: Lower case with underscores. Lead with a letter.

int a_variable;

Functions: Lead with lower case letter, change words with caps.

x = getValue(y);

Macros: All caps.

#define    INPUT_A     5

Structures: Start with caps, underscore.
Structure instances: same as variable. (you could make this caps as well)

Motor_Controller left_side;
left_side->sensor = getEncoder(INPUT_A);