edited.
I use clear Nylon leaders for most of my fishing.....
Some come with swivels attached, Personally, I cut these off before I use them, as I prefer to use a split quick link instead so attachment to the rig end is pretty straight forward, for the other end, the one thats attached to your mainline, I use a Palomar knot, which is one of the strongest wet knots you can use, but also, one that doesnt cut into the fused loop of the leader, which a grinner or blood knot can do! You can also use a loop to loop to join the leader to mainline, but IMO it's not as strong as a Palomar.
Some come with tungsten sections which will keep it pinned down on the lake bed, but having being coiled up in a packet for god knows how long, they don't usually sit very on the lake bed straight away, so I like to stretch mine down the inside of a door frame under tension with a cpl of pins for a few days before use, bit like you do with rigs on a rig board, this usually gets rids of any kinks n coils