It's best to handle valves with a glove. If you do get fingerprints, etc. on them, clean with cotton and Isopropyl alcohol, which can also be used for the contacts.
I have also used Caig DeOxit which is supposed to be very good for all electricals contacts, but haven't found a source for it in India.
Is this a power, pre or integrated amp? Does it have auto biasing of the tubes?