Hello Suzie! If a flight is fuel critical, the pilots are probably a little nervous about 1) doing a full arrival route, and 2) any vectors. I would suggest that when a fuel critical flight first checks on with you, you tell them your plan for the flight, such as planned track miles or location of traffic they are following. If you have to give them a slight vector for spacing, calm the pilots' fears by telling them "turn 30 degrees right, SHORT vector for spacing" so they know that you're not planning on vectoring them all the way to Shanghai before a turn to final.