The single biggest mistake first-time visitors make is queuing at the most obvious entrance at the most obvious time. With twenty minutes of planning you can save two hours.
Buy a timed ticket online
Always book in advance through the official ticketing site. Walk-up tickets exist but the queue can be long. Choose the earliest available slot.
Use a secondary entrance
There are several entrances. The pyramid is iconic but slow. Underground concourse entrances are faster, especially in winter.
Best days and times
Wednesday and Friday evenings (when the museum is open late) tend to be calmer. Avoid Sundays and the first morning hour during school holidays.
Cloakroom and bag rules
Large bags must be checked. Bring a small backpack only. Free cloakroom space is finite, so arriving light saves time at the door.
Eating well, nearby
Skip the museum food court. The neighbourhood west of the building has excellent bakeries and bistros, much cheaper and tastier.