You want a fairly long copolymer tapered leader, a minimum of 12 feet, regardless of rod length. Use the finest diameter point that you think you can get away with.
I catch plenty of trout without greasing any part of the leader, but according to some this is heresy & obviously I've been catching all the suicidal fish.
A floating, greased leader creates lots of highly visible shiny coils near the fly, which in my opinion looks ridiculous when viewed from under water.
On the other hand, a sunk or ungreased leader creates drag which apparently kills your chances of catching, unless you're fortunate like me & all the other folk who always fish dries this way.
In other words, the jury is well & truly out!