Hello there,
I have models where i need to blend two textures using vertex painting UE4 tool.
What is the best shader way to do it ?
Either do it directly in the UE4 () or in your 3d program () 
@ : I stay with UE4 as it is more easy to vertex paint while i man in level editing. There is some other videos but using shader with some little differences , is there any best practices ?
Sorry, but I dont know what you mean? 
The way that is shown in the video above is the best and easiest way how you can do vertex painting.
But when your question is just how you can use two different textures on a mesh, then you could also do it with masks -> use a lerp node or with material slots ->
That’s good to know