Teething toy/Tylenol. Your baby may be the most happy gnawing on his/her own hands more than anything! try a teething ring (some babies like it cold) or a teething toy as well. If your baby seems very uncomfortable, you can try a weight appropriate dosage of Acetaminophen (or Ibuprofen if your baby is over 6 months). Try to avoid orajel or medicated teething tablets; the risk of side effects may outweigh the benefits.
Chew chew. Babies need to chew, especially when teeth are coming in. Chewing on something with a "knobby" texture, or something cool, can help a lot. If you baby has moderate pain, and is irritable, you can use a teething gel directly on the swollen gum, or in some cases, give tylenol (acetaminophen) as directed by your doctor.
Something Cold. There are several approaches.Tylenol (acetaminophen) may help. Local anesthetic such as oragel provides very short lived relief. Take a clean washcloth and run it under cold water. Let the baby suck on this as needed. This works as well as any teething ring as the cold helps numb the area and the roughness relieves the discomfort.