Assume a kitchen sink faucet? Brand? How old?
Usually you'll have to take it apart, clean mating surfaces where parts rotate against one another, fix any torn o-rings in the faucet arm where it rotates around the stationary part, lube it with plumber's grease and it might be better.
If you are talking about the spout. A good rebuild would help. A new set of o-rings lubricated with plumbers grease, would get that thing moving like it should be. The reason I say rebuild is, why bother shutting off the water, and pulling things apart and not take advantage to put all new rings and seals in. If you have a Delta faucet, then a local hardware would have a whole rebuild kit. If another brand then find appropriate kit and rebuild the faucet. Keep in mind, if the faucet is not visually appealing, then maybe its time for an upgrade altogether.