Question About Modeling Low to High or High to Low

[Akaize]

Hi guys, now I need a little help with something.

Today, I model, first the low poly portraid level, then I using subsurface, bevel on the edges to make the model more soft, and then use the sculpt to improve and create more details.

But with this method, I can't use the High poly model to create Render to the Shop, and the texture don't fit well on the high model.

What is the correct method to do this?

My method work, but just for the game.