First, you need to leave them in the packages until you are ready to use them. They'll stay clean that way.
Second, usually a machine shop installs cam bearings for you when you get block work done. If the block is recently back from the machine shop, clean with mild soap and water, blow dry with compressor air, give a liberal amout of wd-40 on all machined surfaces..
the shop did all the block work and did cam bearings, the new cam bearings are in the block ,its all cleaned and honed ready for me to start building...