I'm a certified groomer and have been grooming Yorkies for over 15 years. I've had some very interesting clients too!
The key to grooming is exercising the dog prior to grooming!!! A healthy walk sets the mind at peace and exercises the body leaving the dog more accepting of the grooming process.
It is so important to start very young with techniques. Handle your pups feet often, just gently rub the paw pads, open the pads up and massage their feet. This gets them used to having their feet handled. When trimming nails just cut the tips off - don't go for broke and try to remove lots of nail - it sends a vibration up the leg and while it isn't painful think about how that feels to a dog. I typically will give the dog a bath while they are busy licking up water I clip nails. They are distracted and I get nails done without a fuss.
Brushing - I rarely use a brush on a Yorkie. I use a comb with rubber tips. Brushing just causes static which creates mats. I comb in sections. I start at the rear and go down one side of the leg, always combing slowly and mindful of mats. Most mats can be "fingered" out. Move to other side of rear, then back, under belly and shoulders. I leave the head for last. I comb out the head, put in a topknot. I comb daily - sometimes twice a day.
When I put clothes on my Yorkie I spray the clothes with Static guard first to help keep static down. Just spray - let dry completely and put on clothes.
Bathing - Use quality shampoos and conditioners. I use a product called Quadrups. It is amazing - my clients LOVE it. Use luke warm water and cooler water to rinse out conditioner. Dry the coat - adds shine!
The key really is starting early - using gentle, calm techniques and rarely do I talk to the dog while on the table. Only after I've completed the groom do I offer treats. A reward after good behavior!
Yorkies are so smart - are are some of the most beautiful dogs when groomed. Your calm attitude and confidence in what you are doing will go a long way with grooming too. If you expect attitude from your pup - they will give it!