Right first time: Using SPC to improve RFT

Starting production with the right parameters with low scrap and almost no time consumption is important for production efficiency.
RFT=right first time
RFT is a challenging task for most production organizations that produces many products/parts.
Using SPC is a good way to solve problems regarding RFT.
How can we find the parameter that we can improve, out of hundreds of products and dozens of parameters that each product has in its spec?