what is the best formation ?

Attachment 23350 my team

There is no "best" formation. There are a lot of formations with useful features. I tend to use 4-4-2 classic as my standard and occasionally alter it. This is because it is a very balanced formation that is hard to counter. Others prefer more flexible formation that can be easily switched to various other ones during a match.

How do I use best 3w-4-1-2?

I don't know - I've never used that formation - hopefully someone else will comment here. Skidz?