the official college board tests and some more:
this site has almost all of the official sat exams in pdf, plus the answer sheets. additionally, they have most of the official psat exams.
p.s. it's kind of a weird site. the left click and right click is reversed.
the famous college board sat tests are here: satsuite.collegeboard.org/sat/practice-preparation/practice-tests/paper
of course, these are the ones you should do before any other practice test.
some people may already know this, but the khan academy sat prep page has excellent resources for writing &language prep. don't use their reading quizzes though. that section is crap. the writing and language quizzes are brilliant! here:
www.khanacademy.org/mission/sat/practice/reading-and-writing --you need to sign up first--
varsity tutors has some good sat practice tests here:
the most effective way of preparing is definitely making use of the official exams. especially for reading, there is no other resource that is even close (for the writing section, official tests are the best as well but khan academy is quizzes are close in terms of effectiveness.)
p.s. the link for khan academy writing lang. quizzes:
one of the best things you can do to improve your verbal score is to work on vocabulary. that is, learn more and more worrds that you may encounter in the exam
so, a good way to do this using vocab flashcards. you can prepare your own flashcards ow there are several options on amazon that you can buy, like this one:
you can use digital flshcards that are provided by xome phone apps like this one:
for the writing & language section, the best book to study from is #college-panda . also, the writing and language quizzes of khan academy are very good. just, don't use that website for reading practice.
here are the sat practice tests from princeton review:
you can use this app to study vocabulary in flashcard format:
there are some tests here as well. but, i don't like how they are organized. you might still find some useful stuff : www.cracksat.net/index.html