The simple answer is to
If you clean a coin, you risk completely damaging and destroying its value. A lot of times when people see an old coin as "dirty" it really just has toning on it. If you clean a coin you really risk reducing its value by tens or even hundreds of dollars.
I would suggest you going to a coin dealer first and getting an appraisal of your coins and see if the coin dealer suggests you to clean them. If so, they should have a container of coin cleaner that you can purchase which will do the least amount of damage to the coins. But seriously, do not clean coins, you only risk damaging them and losing money. A cleaned coin will never be worth more than an uncleaned coin (metal detecting finds aside).