If you`re looking to perfect your coffee brewing technique, here`s something to try:
Use two filters, and a coarser grind.
The reason: over extraction makes coffee bitter, and a grind that is too fine results in over extraction (but a grind that is too coarse with one filter results in weak coffee).
However if you use two filters, the water doesn`t pass through as quickly, and the coffee will be more full bodied. That, combined with a coarser grind to reduce bitterness, makes a better tasting cup.
I read this tip awhile ago, and the results were so good, I haven`t looked back. You may have to experiment with the way you grind your beans - I know for myself, over-grinding was an ingrained habit that took awhile to break. I use a re-usable filter, combined with a paper one as well. I compost my used grinds and paper filters, so at least that makes it a bit more green.
Have fun, and happy brewing!