First, it's impossible to hold a jig still in a boat, near motionless is the best you can hope for.A lot of the time that's just right. Boat movement from wake or wind and just being human imparts a little action. Fall rate is also important. If they don't want it on the bigger head, keep dropping the size til they do. One day I started with an eighth and the bite improved as I went all the way down to 1/64 and it was almost a fish on every cast. Also when they are finicky I sometimes don't lift the rod tip to twitch the jig, I drop it an inch and hold it there. It's a more subtle movement that sometimes is just right.