I have always heard that you should not brush their hair while wet (it increases breakage).. instead brush it just before their bath and also not to rub them or scrub with the towel to dry their fur.. i used to do that when i first got kai because i wanted his hair to dry so he wouldnt be cold but now I just hold him for about thirty minutes or so until its almost dry and then blow dry it the rest of the way and his hair is sooo much softer...
also while your yorkie is still a tiny little baby i would wash him in the sink with warm water.. also I like to use a cup to pour water on kai's back so that its not too much. as they get older and you feel more comfy with your baby move to the tub.
.. i hope this helps a little..