One of the nice things about different colors and styles of dice is that you can mix and match them together.
By placing different effects next to each other, both are emphasized, for example. Here, dark glossy marbled green lies next to matt light ivory. 
My favorite palettes often have three or four sets with one set standing out, like this one for Ash, Tiefling Vengeance Paladin.
Like this one. I don't have a character for this one, I just wanted to make something with a fire theme. This one has fire, smoke and ash. 
These three sets have in common that they all have marbled swirls, but the reddish brown set stands out because the other two are much more neutral in colour. Without those two, the reddish brown set is a bit boring at first glance.
On the other hand, sometimes it is nice to use sets together that share many properties. This palette for Jo (a Changeling Rogue in the Eberron setting) is all about everything being grey with glitter. 
These two sets, different Chessex Lab sets, also work very nicely together. 
If you have a strong theme that you want to portray, this works very well. For example, this oceanic palette 
Or you make a progression of dice sets that have a lot in common from set to set, but the extremes are very different. These are four sets. 
Two sets can have many similarities and yet be very different. By putting them together, the similarities become more apparent. 
Hopefully this will inspire you to start matching your own dice. Have fun with the shiny clickclacks!!