Hello, welcome to YorkieTalk.
I also have a somewhat skittish Yorkie but she is getting a lot better. My first suggestion would be get him socialized a little by taking him with you places for example SophieKate goes with me to places that are dog friendly (Lowes and Petco are good examples), I always keep her either in her sling or put her in the cart.
Most important thing is to make him feel confident about new things, if he is scared do not comfort him (I know this is the hard part). For example if SophieKate was afraid of a person I would take her over to the person and explain to them how to approach her (get down to her level, she is short they are tall). If a person wants to pet SophieKate I always ask them to let her smell their hand first.
It's a slow process but over the last 1.5 years I see a new dog, different from the shy little girl I originally got.
Good luck and I am sure others can offer good advice.
__________________ Cheryl,Mom to  SophieKate |