Ben Ross also found himself over the tryline after accepting a short ball from Carney.
The visitors suffered setbacks through first half injuries to McCrone (side strain) and Shaun Fensom (eye).
McCrone's replacement, Milford, cut the Sharks' lead to six when he raced 50m to score, but a long-range try to hooker Isaac de Gois gave the Sharks an 18-6 buffer at the break.
The talented youngster grubbered for centre Blake Ferguson to open the scoring in the second half, and had a double when he backed up a break which he had created.
But a 60m intercept try to Jayson Bukuya, who outpaced Terry Campese to score under the posts, and Fifita's match-sealer ensured the Sharks extended their winning streak to three games.
In another timely Origin audition, Fifita ran for 201m in a powerful display.
Newcastle have put the brakes on their slump in form with a first NRL win in three games, scoring seven tries to see off Canterbury 44-8 at Hunter Stadium yesterday.
The Knights banished the memory of last week's 44-14 capitulation at Canberra, with Willie Mason putting his hand up for a NSW recall with a powerful performance.
Sharks 30
Raiders 20
Knights 44
Bulldogs 8
- AAP