Most of my customers use drip brewers as their method of making coffee. With that in mind I am going to take a brief moment and make sure you are aware of a few easy things you can do to make sure your drip is as good as it can be!
Clean your brewer. Be honest, when is the last time you ran a cleaning solution through your brewer? You would be surprised what builds up in those machines, and bare in mind you are DRINKING that! Coffee Cleaners are cheap, and can be bought at Wal Mart, so no excuses!
Use good water. Coffee is mostly water, so it makes sense to use a good filtered water when brewing. This is by far the easiest way to up your coffee flavor, and cheapest.
Use more grounds! This is true for any brewing method, but I find drip brewers are the most guilty of using too little coffee. It's as simple as this, bitter coffee usually comes from over extraction of your coffee grounds, so put more coffee in the basket before you brew! (if its too "strong" at the end, add water after you brewed! Trust me!). See Coffee Tips
Grind before you brew. You know how fresh ground coffee smells really good? All those things your smelling are flavors leaving the coffee and going into the air. Those flavors should be in your cup, so grind right before you brew.
Change your grind size. Mess around with your grind size and find the right size for your brewer, this will change depending on several factors, and trial and error is the easiest way to determine what is best for your machine.
Stir your grounds if able! Check one day after a brew to see if your drip is actually getting all the grounds in your basket wet. If it is not, you may want to try stirring the ground while it is brewing, WITHOUT getting burned (PLEASE TAKE CAUTION!). Depending on your model, this can be as simple as shaking the basket while your coffee is brewing, or shutting off the brew and stirring the grounds. This will ensure all the grounds are getting extracted from!
I will post up some pics of the drip brewer I use here shortly to show some examples of a few of these tips!