I agree with Mr. Snell on everyrthing he mentioned. The reason you want to switch to a conical burr grinder is the uniformity of the grind size. With a blade grinder you get freshly ground beans, which is great!, but the grind size is all over the place. This causes the grounds to extract at different rates, the smaller grounds going quicker than the larger grounds due to the surface area vs volume of individual ground. This also causes some grounds to get over extracted and some under causing the grounds to impart different flavors to the brew, i.e the over extracted grounds causing your brew to be bitter. Having a conical butt grinder helps greatly to improve the taste of your brew!
All of his other suggestions are spot on for greatly improving the taste of your drip machine. If you want to switch up your brewing method I recommend a French press if you generally buy darker roasts because the long steep time really helps bring out the long roast flavors with the longer contact time. If you like lighter roasts than the Chemex pour over devices are phenomenal. It brews a really clean, bright cup of coffee that really highlights the flavors of the beans from shorter roasting times.
I get a little carried away talking about coffee, if there's one thing you can do to really improve your coffee it's to get freshly roasted beans. If you want to change things up then the second thing to do would be to get a conical burr grinder. And for free just do some research on coffee brewing, since it's free you get a huge return on investment! With those three things you can make pretty great cups of coffee with a drip machine!