It really depends on the material that your contacts are made of.
If your contacts are gold plated, than cleaning is very simple because gold is not reactive and does not oxidize or corrode. The major contaminant that coats a gold surface are hydrocarbons, although there may be some salts that are on the surface from hand contact. None of these are chemically bonded and are easily removed with any alcohol; methanol, ethanol, or isopropyl. More aggressive cleaners are not needed for gold plated contacts.
If your contacts are copper, silver, brass or another metal than a more aggressive cleaner like Deoxit can be used.
If your contacts are gold plated, than cleaning is very simple because gold is not reactive and does not oxidize or corrode. The major contaminant that coats a gold surface are hydrocarbons, although there may be some salts that are on the surface from hand contact. None of these are chemically bonded and are easily removed with any alcohol; methanol, ethanol, or isopropyl. More aggressive cleaners are not needed for gold plated contacts.
If your contacts are copper, silver, brass or another metal than a more aggressive cleaner like Deoxit can be used.