How do i blindly memorise where the keys are positioned?

I'm now learning semi-tones in sheet-music and i came to a problem whereas i keep looking at what keys to press whilst looking at the sheet. I learned that looking up and down constantly is a bad habit that sheet-readers should avoid, but i have a hard time trying to figure out on what to do in-order to instantly memories what key i need to press without looking my keyboard.

I tried the blanket method but only used that on a practice piece but i basically just memorised where the keys we're because i constantly looked up and down during practicing, then it was basically just sound that leaded me. Althought i really haven't recognised ALL key sounds so what do i do?