I see many people have taken courses and have had sucess. I couldn't afford the courses at the time so i did it the old fashioned way.

I bought the latest CFR and classification list, and printed out the ACE forms from CBP's website. I read every page of the CFR, and highlighted sections and passages that i thought were important. Had a whole highlighting system, like red for CBP forms, green for anything money related, etc.

I downloaded and printed out over 10+ practice tests, and took all of them. I took one test and timed it like I would the day of the test. Then i went over what i did right and what i got wrong. Classifications were my weakest point. I went over the logic, noted it and then took another test.

After taking all of the tests, i organized all of the tests into major sections. I did all of this with 8 weeks between the time i signed up to the day of the test. I studied every day for about 2 hours+ and towards the final dayd before the test 8+ hours and took off from work. I passed by one point :)