Avoid the queue and buy tickets in advance. Some companies selling tickets also offer a hotel pick-up service.
The bath is big and beautiful, but since there are thermal pools, kids under 2 are only allowed to swim in one pool. Bringing food with you is both allowed and recommended.
Go early in the morning and during weekdays to avoid a lot of people.
While the bath is used year-round, its hot thermal water might be more enjoyable in the cooler seasons.
The Budapest Card offers a discount (20% off).