Hey jeff if i am going to a crank bait directly i use a #8 eagle claw
lazer power swivle rated for 50lb they are tiny there is no snap on it i tie fire line to one side then tie the florocarbon to the other end still about 6'-8' then a double lock snap at the other end and connect to the crank so that i can change the lure quick.

If you are going to a spinner or spoon then insted of the snap i would hook up a swivle and connect to that .

Good luck!