While ganking, consider aiming Dredge Line at nearby terrain and following it up with Riptide for a higher hit rate.
Riptide has a delayed blast timing on activation - you can use this while running away or when enemies are incoming to serve as a deterrent.
If Nautilus uses Riptide right next to you, hold in place until the ripple effect finishes before running. Running early will run straight into the secondary explosions, causing you to take additional damage and slow.
While Nautilus is shielded, he is capable of dealing large amounts of area of effect damage with his basic attacks - consider taking down the shield if you have time.