In my personal experience, a RC should be something you find a connection with, even better if it will be something you will easily recognize in a dream.

For me the color blue is prominent in my dreams, that is to say it stands out more than other colors and sometimes seems out of place. I've made it a dream sign and whenever I see vivid blue in reality I do an RC, which usually involves touching the colored object.

You need to find signs and RC methods that work for you. If they don't hold any significance for you they will fail to work.