Rule #1:

DO NOT take the words of those who claimed anyone can pass by cramming for two days right before the exam. Even an experience tester may be caught off guard by this exam because they may have different opinions or views on some materials.  You are strongly encouraged to study the Syllabus thoroughly before even attempting the exam.

Rule #2:

DO NOT practice sample exam papers from online sources!   There are many sample exam questions online and I suggest NOT to do any of them as there are many INCORRECT solutions. Moreover, some questions are misleading since they do not even follow the ISTQB Syllabus.

Rule #3:

DO buy a textbook.  I recommend Foundations Software Testing by Graham, Veenendaal, Evans, Black

Not only it covers all the materials from the foundation level syllabus but also includes sample exam questions at the end of each chapter.  In addition, it also includes a mock exam at the end of the book.

The latest version of this textbook is 2007, but it still covers the 2011 syllabus very well.

Rule #4:

I would suggest this textbook if you need additional sample exam questions,:

Sample Exam Questions: ISTQB Certified Tester Foundation Level by Estrella, Estrella.

They are more difficult than the actual exam but it further enhances your overall knowledge on the subject.

Rule #5.  

DO REMEMBER, you WILL NOT be able to find the actual exam questions online or even from the sample exam questions above.  Actual exam questions are highly confidential and ISTQB does not disclose to the public.  Therefore, you need to STUDY THOROUGHLY the materials by going through the syllabus, textbooks and online tutorials .  The sample questions are used to measure your level of understanding and your progress.  DO NOT Blindly memorize multiple choices questions and answers.