Sorry for the late reply.
Has it got an R8 spindle? Then you need
everything with R8 in its name.
I like ER32 - collet blocks, spindex, chucks....
I got a BS-0 DH, that was "supposed" to have a B&S-7 taper, but has MT2, which is wonderful as I treat MT2 the same way as R8 - if it is in the name, it is a needful thing. Sad though, I would prefer a BS-2 Universal DH for helical milling but 1. It's a major cost (800+), and 2. it's a B&S-10 taper
Find your tapers, buy everything with that taper, and everything that bolts on to everything with that taper.
Convince yourself that workholding is a universe unto-itself, and undertake to conquer that universe.
Recognize that metrology (and metroloscopy) is a vital-shop on its own - it will cost about as much as both a mill and a late. Get the things that tell about the tiny things!
Fowler makes a rather neat optical comparator with changeable reticles. Not an LED, but it comes with a C battery powered flashlight (are C batteries even still made??)
Seriously though, look at it in categories: Taper, Work-holding, Metrology.
When you've gotten all that stuff, then... start over
