how to clean this coin?

I have several Kenyan 5 cent coins from the 1980s with bust of Daniel Toroitich Arap Moi facing right that have some sort of tarnish on them.  How can I clean them?  Thanks in advance!  

These are the coins I have.  Some of the discoloration is greenish - some is brownish.  Sorry they are not better photos - my phone doesn't take very good pictures.  I'd like to clean these up to give to a young man to get him interested in collecting.  I am actually not a coin collector.  

What do your coins look like?  Brass tarnishes. That's natural. Probably best to leave them alone.

Interesting coin. Almost all the letters are like double strike. Was it intentional? 😁

Those are the pictures already in Numista. And yes, interesting.

I've posted photos of the actual coins.  Thanks!

You actually have verdigris on some of those. It can be a big problem for the coins. 
 Most coin collectors are against cleaning. but these are of no value so it’s not a big problem. You can put some oil on them to stop the oxidation that is causing the verdigris.