Grammar paralysis: Genitive vs. Accusative when talking about daily needs

I’m a busy professional with 20 minutes a day, and I’m hitting a wall with case endings. Whenever I try to order coffee or describe a daily routine in Russian, I second-guess every single ending. Is there a mental shortcut to prioritize the most 'essential' cases for basic communication, or should I just keep grinding through the entire declension table until it stops hurting?