House Plant pruning

I have two very old Jade plants (money plants) that are now enormous as I am terrified of taking cuttings from them, losing them (and to me they represent the two income streams that I currently have!!!!!) Silly I know but now they are really so big and not looking very healthy.  I feel I should take the decent looking bits and plant them up separately (and make lots of income streams!!!) What would be your advice please and if appropriate when would be the best time to take cuttings and what potting medium should I use.  Many thanks