You don't mention the grade level of your daughter. Generally, the burden of studying is on your daughter. You can help by showing sympathy and support, and being sure that she has a comfortable, quiet place to study. Assuming she is being tested on material covered in her school class and in her textbook, I'd make the following suggestions:
1. She should re-read or skim over her notes and text, highlighting in her notes the important content and adding more notes taken from her text that aren't already in her class notes;
2. She should do this for about 60-90 minutes the night before her test;
3. She should NOT stay up late to do this but should go to bed and get a good night's sleep so her brain can let this information "settle in";
4. She should eat a good breakfast the morning of the test.

If she does all this and is still failing in these subjects, you might want to  hold a parent-student-teacher conference and ask her teacher what more she can do to pass the course(s).

Good luck!  Michael Bentley, Expert Panel Member