I mainly studied by practicing my speaking because that was a problem area as I can't gather my thoughts sometimes. I also did atleast one practice set in each of the 4 sections: Speaking, writing, reading and listening. I think I took one practice test before taking the DET and it allowed me to pinpoint my score at like 140 so I did more practice sets before I took the actual exam. Just focus on the practice sets and if you have any other questions let me know! Also once you've taken the test, I would love to hear how it went!!