Things to look for:

Tail of the R on the inlay, is it pointed or rounded with a ball

Edge spots, none, or some with color

Size of the hotel's crest on the inlay

Base color of the chip

Style of the Hat and Cane in the mold, long cane or short cane

Surface of the Hat, is it shiny (Cristy and Jones) or matte surface

There's also a picture of different chips referenced in the appendix of TCR, page C12.