Tamiya colours are my best preferred ones even if I use often Xtreacolous, Lifecolor, Hataka and Vallejo Air. The main problem with Tamiya is to find the proper Fderal Standard reference.
Searching in the web I found this intersting link http://ipmsrealcote.pro-forums.org/t832-tamiya-mixes-for-some-fs-colors-full-up-to-date-list-in-english
Ezio