This block was designed for big bright patterns....not close colours for the individual blocks*
...opposites attract in this case!
Look at the colour wheel and choose to place orange and blue next to each other , lime and purple, turquoise and red
Ive seen this done with fruit and vegetable prints to great effect, KF is a godsend for this block but I have also seen very subtle versions using washed out rainy colours...I'll see if I can find some pics....
* If you are using more than one colour per block, then they have to blend together.