Preparing for a new puppy is as exciting as preparing for a new baby.  I'm a breeder of yorkies and I have been for over 25 years.   Since this is a very small breed I'm overprotective and that's a good thing...and my advise to you should be embedded in your brain.  It only takes one little thing that could mean the different of life or death for your puppy in your house.  So. when you are gathering your supplies also think about your house and make is pet safe.  I will give you a big list here to on what supplies to get to make your home safe.  Okay, now here is my big list of pet supplies that any new doger owner should buy.
1.  Dry Kibble (Iams Smart Puppy specfic to the breed is a good choice).  Later, I recommend adding human quality food to their diet.  This includes meat, poultry and vegetables.  Be sure to read the foods you should avoid on my list. There are numerous cook books for dogs.  Canine cook books are well worth buying.  You'll save money on dog food and will be doing your dog a big favor.
2. Dog bowl for water, dishes for food.  Stainless steel dog bowls are really the best because they are non-porous and are easier to clean.  You want to make sure that when you use the bowl, scrub it with soap and rinse it thoroughly.  Never just keep adding water to a bowl.  Water becomes contaminated with air particulates (dust) that rests on the bottom of the bowl.  It also can grow a slime.  Obviously, dust and slime aren't healthy....so wash those bowls!!!
4. A fluffy bed.  Depending on the size of your dog, small dogs like snuggle beds, larger ones need bigger beds.  They should be able to stretch out.
5. A crate (big enough to hold water and food and wee wee pad)
6. Wee wee pads.
7. Chew toys (pig ears are great).
8. Squeeky toys, Balls.
8. Harness.  Harnesses are way better than collars that could actually strangle a dog.  9.  ID tag (you can get these from most any pet supply store)
9.  A leash.  There are 2 kinds, ones that retract and expand and fixed width.  Depending on the size of your dog, get the appropriate size.  Tiny dogs, like yorkies, need the lightest weight you can get...cat leashes are good.
10. A warm coat.   A dog coat will protect your dog from the wind or the rain or cold....so button their little bodies up and keep them warm. 
11. Toothbrush and toothpaste.  This is especially important if you feed your yorkie wet food.  It's easy to do...follow the instructions on the toothbrush/toothpaste kit.
12. Tearless Puppy Shampoo.  It's easy to get them to enjoy bathing by making is pleasant and giving them a reward such as a small  piece of cheese (during and after).  Never put water or soap on your yorkies face.  Wet a wash cloth with warm water and clean it that way and only that way.  After a few times in the sink, your yorkie will learn that bathy bath time is fun!
13. Small hair brush.
14. Small elastic bands for pony tails if you have a dog that's going to be wearing bows.
15. A book or two about the breed of your dog!!!