When doing seminars, I always leave time for questions. Over the years, the most frequently asked question is "How do I attach Braided Line to Fluorocarbon?"
There are many ways to make this connection successfully, but if my life depended on the strength of this connection, I would tie a Bimini Twist in the Braided Line and then use a Double Uni Knot to connect the two lines.
The Bimini Twist doubles the line making any knot you tie stronger than it would be with a single line. The Bimini Twist looks difficult upon first seeing it, but I assure you that it is not difficult. You can see how to tie it step by step in this article and video.