I'll tell you what I wish I knew...the practice exam on feprep.com is the exact same test every time you order it, so I wouldn't order it more than twice. The quiz bank is useful because it is very versatile in the content and you can mix it up with qualitative and non-qualitative problems. The flash cards helped me with memorizing identities and formulas so that I didn't need to rely on the reference manual very heavily during the exam.
I would buy the practice exam and take it once immediately (you get two attempts per purchase) and use it as a baseline for what you need to focus your study on (I scored a 38% on my first run with no review or study) I took the second attempt 3 weeks later and scored a 70%. I bought it again thinking it would randomly generate a whole new set of questions, but it didn't. I studied a few more weeks and took it again, and kept scoring 70-80% and thought, "Well, it's because I know these problems now and I know what the answer is supposed to be," but I forced myself to work out the solutions every time even though I remembered the correct answers. That was when I decided to buy the NCEES practice exam and assessments. It was a fresh set of questions, and much to my happiness, I found them much easier to solve than the feprep.com practice test. I scored 80-90% on their tests.
Obviously, I don't know what I scored on the FE exam, but I passed and felt half-and-half to pretty good about it when I left the test center.
The Lindburgh book has ten assessment questions at the beginning of each chapter, which you can use to gauge your proficiency with the material covered in that chapter. There is not a comprehensive "test" available in the Lindburgh book...that's why they sell the practice tests.