Lots of ways to skin a cat depending on what you’re doing.
What is your main line?
Are you using mono with riggers or snap weights?
Braid with a leader?
Leadcore?
Copper?
Wire? Dipsys?
All of them need to terminate with a snap swivel, but I vary the size of it and pound test of the leader depending on the application.
Spoons run better (more action) on lighter leaders like 15-20lb, but 30lb isn’t too heavy either.
Most of my reels have have a 25′ leader at the beginning of the season. I like to attach the leader to the mainline with a 50lb or 80lb Spro swivel.
The 50lb will reel through almost any levelwind, the 80lb won’t fit through some reels with small levelwind eyes.
It’s not completely necessary with spoons, but doesn’t hurt (you definitely want it if running flashers
, dodgers, or Brad’s cut plugs).
You can also do a Willis knot instead to connect leadcore to the leader, or choose one of many other knots to connect it to braid (like a Crazy Alberto). A uni-uni works well if connecting it to a similar sized line (like a mono mainline).
Run true fluorocarbon “LEADER MATERIAL,” not fluorocarbon LINE. It’s much more abrasion resistant than line.
I like Seaguar STS. It’s pretty reasonable ($$) as far as leader material goes.