Because most faucets are set up in the same manner, fixing a leaky faucet will generally be minimal in cost and easy to do. If you have city water, it also will save you money because you will no longer be wasting water that you have not used.
The first thing you want to do is shut off the water supply to the sink. Most generally you will find twist handles for this located on the underside of the sink itself. To avoid the hassle of having to fix a leaking faucet, you should get the Best Kitchen faucets installed at your place.
Once the water supply has been shut off, turn the faucet handles all the way on to allow any water remaining in them to drain out.
Now you want to disassemble the faucet to get to the problem. Take the flat end of a straight head screwdriver to carefully pop off the top of your faucet handles. Place them to the side for later use. Place a light colored cloth in the bottom of the sink so you can see any pieces that fall here while you are disassembling, and make sure as well, that no small objects fall down the drain. This will also help ensure that you do not inadvertently chip the sink while you are working.
Unscrew the screws that are in the faucet handles and gently pull them out of the sink. Take the washer off that is present and replace it with a new one that is identical in size. If a washer is missing, purchase one at a hardware store. Most generally this will be where the problem comes from when a faucet is leaking.
Once the new washer is in place, reassemble the faucet handles and then test the sink. If all is well, replace the decorative pieces that cover the screws and congratulate yourself on a job well done.
If your sink is more complicated, such as a sink that has a rotating faucet ball, you will need to adjust the above directions slightly. Follow the directions above for disassembling the faucet (remember to keep a towel in the sink). While the handles are off, check the ball to ensure it is not damaged or corroded. If it is either, you will need to replace it. If you do not know the make and model, take your existing set to the hardware store to purchase the proper size replacement. You also want to purchase new springs and a seal, while you are already working on the sink.
Once you have the new parts purchased, remove the old springs and seals from the faucet handles. If there is gunk or corrosion after removal, carefully remove it before putting in the new parts. The cam and ball replacement for the faucet will be self-explanatory for replacing because you will see where the parts are meant to match up. Assemble accordingly. Test your sink. This should have alleviated your leaking. This works in most cases, but if for some reason, the replacement kit has not solved your problem, you may consider calling a plumber.