I have had a couple Yorkies who have just plain hated being combed at all and it was a total struggle to get the job done.  So I decided to try a little trick I learned when training my African Grey Parrot to accept a harness.   What you do is basically a step wise desensitization method.  With parrots you begin with something as basic as sitting the harness next to the bird and doing nothing more than that.  With a yorkie puppy you may start with just touching them with the comb upside down so the teeth are facing away from them and just sort of mimic combing them until they relax and allow it.  Since there is no pulling from the teeth they will usually allow this.  Remember the goal is to get them to enjoy the excercise and not fight you.   Then slowly begin to comb them but when you reach a tangle stop. You can always cut the tangle out as its only hair and will grow back.  If the dog learns to hate being combed you will have years of having to contend with the problem.  

 

 

The same thing applies to nails.  Always leave the nail longer than you think you should because its better to be sure you don't cut the quick as that will make the dog lose trust in your abilities to do the job.  The vein will shrink back after you cut the end and you can come back the next day and take a little more off.  Remember slow and steady wins the race.