Put information in context. As my brother would say, "information without context is meaningless". In the sciences for example, remembering formulas is much easier when one understands concepts through hands on experiments.
Same with math. It's easier to remember equations when one understands the underlying concepts.
If your child has to learn a list of things quickly, it helps to "associate" the items with something that is familiar to the child. This can also be done using songs or rhymes.
Repetition is important. The child should go over the "stuff" several times. And this includes "touch up" reviews every now and then, as reinforcement.
The bottom line is that there is no substitute for EFFORT. One has to put in the work to get results. Believe it or not, the difference between an A student and a C student is (most likely) not intelligence based, but rather, one is willing to put in the hard work while the other is not. Obviously there are exceptions.
Good luck.