Build the rear section first: mount a trailing hook on an articulated shank and tie in a full marabou tail with flash. The rear section should be about one shank length of material.
Connect the front hook to the rear shank with a wire loop or interlocking shanks. The connection should swing freely. This hinge is what creates the swimming action.
On the front hook, build a body with dubbing brush or chenille, wrapping forward to the 60% mark.
Add a collar of marabou or flared deer hair.
Tie in dumbbell eyes on the underside or top depending on your desired orientation.