The 'li' vs. 'na' vs. 'me' tense marker dilemma in fast-paced conversation

I am a grammar-focused learner, and I have the conjugation rules down on paper, but my brain freezes the second I have to choose a tense in an actual conversation. When I'm talking to native speakers, I find myself pausing for too long trying to calculate the correct marker. Does anyone have a mental shortcut or drill that helps make these prefixes intuitive for real-time speech? I am asking specifically about learning Swahili, not a generic study routine.