There are a lot of ways to create a natural looking free edge. Everyones free edge has a different shade. I wouldn't go blindely with 1 mixture and use it on everyone but mix up a base mixture that you can alter by comparing it to the customers real free edge. In this way you can add a bit more yellow, clear, white, melting pot, pink etc... to get the perfect shade.
I do this all the time when a customer comes in for a *natural* new set. When their own nails start to grow you can bearly see the color change between the tip and their own free edge. Also handy when a customer breaks a nail and you can replace it without it showing