Okay, lets start with the basics, there are a few critical rules to stick to for good coffee, here is the 101:
Store your coffee in a cool, dark, dry spot... for example the low shelf of your pantry. Heat, moisture and light is the enemy of coffee, heat and light will speed the aging process while contact with moisture will spoil the coffee. The fridge is a giant no no for coffee storage due to the moisture created by condensation.
Buy a grinder. Once coffee is ground it is on the fast track to going stale, within 15 minutes of grinding the quality of the coffee has been significantly compromised. Depending on the brewing method grinders don't have to be expensive (although for espresso, more expensive grinders definitely help!) but they do need to be a burr grinder. Consistency of grind size is important for each brewing method. Spinning blade grinders (sonetimes called spice grinders) are a not usefel as they have no consistency in grind size, don't be tempted.
Scales help if you really want a good brew. I know it is so pedantic but honestly the only thing preventing most people from a good cup of coffee is dosing the right amount of coffee. Small digital scales are pretty affordable and are a worthwhile investment to take the guess work out of home brewing.
Buy small quantities. To get the best out of your coffee it is ideal to buy your beans in no more than a fortnightly pattern, weekly is even better. Much depends on your brewing method, the effectiveness of your storage and the environmental temperature. We generally regard the window to consume espresso being 4 to 14 days (optimum 7 to 11 days). Past 14 days the quality starts to degrade, bitter tones will become more prominent and stale flavours will become more obvious as acidity and sweetness slip out of the taste profile. Filter, plunger and syphon brewing is better fresher, I would recommend a 1 to 10 day window, acidity is critical for these methods and acidity is more noticeable in fresh coffee.
Buy beans appropriate to your brewing method. Good espresso coffee generally does not make good plunger or filter. Ask your roasting company for advice! Sometimes we encounter the theory that darker = strong and strong = good. What we try to do in roasting is bring out the optimum flavours of each coffee origin. Sometimes this means roasting quite light particularly with better quality coffee. You experience much more flavour and complexity in filter, plunger and syphon coffee when it is roasted lighter. Softer brewing relies on more acidity retained in the roasted coffee. Espresso requires a different roast level, due the the speed and pressure involved in the extraction process the coffee normally is better roasted a bit further than for filter and plunger. However our view at Espresso Workshop is that 'dark' roasted coffee is not desirable for any form of brewing method. Once you reach a stage where oils are coming to the surface of the beans any beneficial flavour qualities inherent in the beans has been effectively baked out or overcooked.