I have dark brown hair i do get my pieces matched with my hair sample but i still color the piece and my own hair. i use wella medium ash brown. with a violet color drabber to deal with the red tones. The trick to getting both your hair and piece as close as possible is trail and error really.

I color the piece and my own hair separately the timing is crucial i only leave the color on the piece for 1 min 30 sec after i have applied. The piece is like a sponge and will take the color really quick. i then put the rest through my own hair but leave that for 25min's

Have a look on youtube there are loads of vids on how to color hair systems what to use and what to do.

Happy Experimenting it takes time to get it right.