Use a loop knot to tie on the plastics. I never really liked using swivels, and the loop knot helps a lot. Are you using a spinning reel? If so, when you put new line on the reel make sure it goes on counter-clockwise. Put the spool of line on the ground with the label facing you.
I don't like adding any other hardware to a softplastic than neccesary. If your using something that spirals through the water, you need to get better at rigging them straight. Assassin's are the hardest and will spriral some regardless, but the straighter they swim the better. Start holding the rod high with a length of line out and let the lure untwist before the next cast. Each cast that you make without doing this, sends the twist further and further into the spool. I think you already know what happens next. Our try using Fireline. That stuff behieves well on spinning reels.
"I don't like adding any other hardware to a softplastic than neccesary"
A small Spro and small split ring makes no difference. I was taught this by a buddy that guided in Rockport for 12 yeas, and now fishes the Red Fish Cup, second in Galv. last year, he is the best fisherman I know. He uses them this way, doesn't seem to bother the fish he catches, lol. I have been doing it since 98 and I can say it doesn't bother the fish, even in clear winter early spring time water, or in the Laguna. Plus you won't dip the lure into the water on the back end of your cast and bird nest because of the long leader you can't reel up because of the in-line swivel. Just tie a surgeons knot if its mono to mono and a uni to uni if it is braid to mono leader. Like I said before then your leader will last all day cutting and retieing your lures.
I use a Small spro swivel and speed clip attached to the jighead, and then tie a double surgeon knot to connect my leader to the main line. Doesn't effect the lure at all and eliminates the line twist. I am also real meticulous on rigging my plastic on the jighead, goes back to my freshwater Texas Rigging, if it ain't straight it will twist swivel or not.
I can attest that letting the line out behind the boat will take the twist out of the line. Let out just a little more than what is twisted. You don't need to go very fast.....just cruise for 3-4 minutes and the job's done.
Caution: Make sure the boat is moving...and it's moving in a straight line before you start letting the line out. If you let it out before moving and have to correct your heading, you run the risk of the prop catching the line. If you think a Jack will spool your reel quickly, the prop will spool your reel in just a few seconds and you run the risk of your rod tip getting into the prop action.
Small barrell swivels don't seem to reduce the quantity of fish at all and saves all of this effort.