Hopper Dropper is a very effective method to fish either out of a boat or on foot. To set this up on your leader, first check the length and the leader diameter. You don't need to go too long on the leader to Hopper connection nor too light with the tippet size. For most hopper dropper rigs, I like to start with 2x or 3x to my hopper and about 6 feet from my butt section to my hopper. If conditions merit it I will drop to 4x to my hopper, but that is a small as I willl go on the initial part of my rig.
The dropper part of the rig is not always the same but the basics are 2 – 3 feet of tippet to my dropper in a size smaller than what I am using to my hopper. For example, if I am using 3x to my hopper then I can use 4x (or 5x) to my dropper. Depending on what State I am fishing in and the regulations, I may add a 3rd fly, if allowed, on another piece of tippet below my 1st dropper. This 12 -18 inch section can be another piece of 4x or a section of 5x if i need to drop down a size.