Hey UMRU,
This is one of the areas I've worked on as an area of research for a number of years. (I'm a professor with a degree in measurement, evaluation, and statistical analysis.) Also, have tutored a number of friends' kids.
Here's the deal. The SATs are a set of questions to be solved. There are a number of underlying formats for those questions (reading comp, sentence completion, etc.). In recent iterations of the test, ETS has moved toward making them more closely related to school subjects. When I took them (1967!), they were basically an IQ test based on your reading comp, vocabulary, and ability to solve math puzzles only marginally related to school subjects.
With regard to the verbal questions, it is important that your daughter is super familiar with the format of these questions and has a well-practiced "attack strategy" for approaching them. She wants to learn how to address these from someone who knows what they are talking about. She then needs to really rehearse those formats. Other than that, on the verbal questions, studying things like vocabulary is not really super helpful as the chances that something she studies will actually be on the test is pretty small (too many words in the English language!). But, getting her approach to taking the test down pat is key.
On the math side, it is a bit of a different story. Here, practice is key. The math questions come in several different varieties, but the superficial format looks the same. But there will be straightforward algebra questions, geometry questions, etc. Then there will be math puzzle type questions. This is where the rubber meets the road on getting a good score. A good tutor will show her how to "unlock" a number of these types of questions, and then, and this is key, she has to practice. It's like working on your jump shot. The more you do it, the better you will get, and (and this is key, too), the faster you will get at them. If you can knock off the easy ones faster, it gives you more time for the others, and also will cause you to panic over time less. You basically want to knock the rust off of your skills, and pick up some new ones.
If I lived closer than 10,000 miles away, I'd be happy to do an hour session with your daughter and check out her test-taking skills. Most kids are "OK" at test-taking, but could use some sharpening up. Some kids have awful test-taking skills, and I can pick those out fairly quickly.
One final thing. If she is going to take practice items, have her do it from real SAT items, not the ones that the companies who sell books make up. They are often crap at making up those items. They look superficially like SAT items, but they don't really measure the same skills. Also, don't listen to their claims of improvement. A lot of what you see in improvement is called "regression to the mean" due to measurement error. I could explain it, but it would take another post as long as this one!
Best of luck to your daughter, and if you have any questions, feel free to send me a personal message on the board.