Granite worktops are a great choice and one that is becoming more and more popular. The attractive stone is durable, both water and fire proof and can withstand most substances. (Having said that, though, do avoid using vinegar, lemon juice or ammonia based cleaners on your granite as these will bleach and mark the surface.)
If your granite surfaces are looking less than pristine, here is how to clean them properly. First of all, clear the entire surface so that you can work over the whole countertop at one time. Brush off any loose debris, such as crumbs and dust, leaving the counter relatively clear. Next, examine it for any stains or crusted on food. Take a damp cloth and wipe over the whole surface to remove these, and also to sweep away any small particles that you might have missed earlier.
If some stains remain and they will not come off with a damp cloth, then you can use a paste of bicarbonate of soda (baking powder) to remove them. If your stain is oil-based mix the bicarbonate of soda (approximately one cup) with about 5 spoonsful of washing-up liquid and enough water to make a thick creamy paste; if it is water based, swap the water for mild hydrogen peroxide. Patience is required here, you must apply the paste to the stain, cover it with a piece of plastic wrap and leave it for at least 12 hours, after which time the stain should simply wipe off.
The next step, after all the stains have been removed, is to clean the whole surface. You can use household washing-up liquid and warm water and simply wipe down the surfaces with a scrubber or cleaning cloth. Work methodically from one side to the other so as to be sure that you have not missed anything.
Rinse your cloth in clean warm water and wipe down the counters again, this time aiming to remove any soapy bubbles and as much water residue as possible.
Finally, dry off the counters with a clean soft cloth or a few sheets of kitchen towel. It is a good idea to apply granite sealant to your granite surfaces periodically to keep them resistant to water and staining. Replace all your appliances and pop the kettle on to have a nice, rewarding cup of tea as you admire the fruits of your labour!