REFERENCES: http://www.furaffinity.net/journal/3334566 (including reference sheets, written description, etc)

tail colouration:
yes, the colouration is different from the main colours. this is correct.
the tail is mostly natural tones of white, cream, black, grey and brownish tones.
think of raccoon, wolf, kit and grey fox tails.
if it is easier, you may opt for either this design, or an ethiopian wolf tail.
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the tail design does not need to be exact and can be altered or simplified within reason. feel free to discuss it with me if you are unsure.