Most advice about brewing coffee is written for cool, dry kitchens. Karachi is neither. Here is what actually moves the needle when the room is 34 degrees and the air is heavy.
Grind just before you brew
Ground coffee goes flat within days, and faster in humid air. If you own a grinder, this single change will do more than any new brewer.
Reseal the pouch properly
Push the air out before you close it. Keep it in a cupboard, not on a sunny counter, and not in the fridge.
A fresh bag stored badly will taste worse than an older bag stored well.