How do I optimize my Ford Transit Custom's fuel efficiency?

I recently bought a used Ford Transit Custom and I've noticed that it's not as fuel efficient as it should be. What are some tips I can follow to optimize its fuel efficiency and save money on gas in the long run?

Keep your tires properly inflated and check them regularly. Under-inflated tires can decrease fuel efficiency by 0.3% for every 1 psi drop in pressure.

Avoid excessive idling and try to warm up the engine for no more than 30 seconds before driving.