Coffee is like really good bread: no matter how you store it, it never tastes as good as it does when it's fresh. Whole bean coffee tastes best within the first week after it's roasted. If it's ground, coffee goes stale even faster. We recommend you use ground coffee within a few days, at most.
If for some reason (e.g., apocalypse, ice age, giant bees) you must store your coffee, keep it in an air-tight container, in a cupboard or pantry, away from heat, moisture or direct sunlight.
Use two level tablespoons of coffee for every 6oz of water. For 1 litre of coffee, this means you need eleven tablespoons. If this is more than you normally use, try it out. You'll notice a big difference.
Always grind the coffee right before you brew it, and make sure to grind only enough for the coffee you're making. This makes a huge difference in the coffee's flavour, as all the subtle aromatics of the coffee are still present. The best investment you can make to improve your coffee is a good grinder - even more important than fancy brewing equipment.
The coarseness of your grind depends on how you're brewing the coffee. The general rule is, the faster the brewing method, the finer the grind. Fast brewing methods like espresso require a very fine grind, while slower methods like French press or percolator require a very coarse grind. Drip coffee requires a medium grind.
Coffee brews best with very hot water. Water just off the boil will work best (just after the boiling sound subsides). Automatic drip machines usually don't get the water hot enough, so the coffee's flavour isn't properly extracted. 
Your best bet is to use a French press or a pour-over cone filter, which allow more control over the water's temperature.
It's also a good idea to pre-heat your cups before you serve the coffee. Just pour a bit of hot water in them, then pour it out. No one wants their coffee to get cold too quickly!