I've been studying for the BSCI exam in the last month. I've read the Self study guide twice, now I'm starting to review the whole materials by making the exams in the Exam Certification Guide, but I can remember too many details, making me feel that I'm not well prepared.
Topics such as SONA, IIN, etc...as they where the first topics, now is difficult to remember details..
Any advice or tips? so I can feel more confident about it?
Don't worry about SONA, IIN, etc because they are not on the exam. It is good to know them, especially about core, distribution, access levels, etc (which will be in your BCMSN studies), but not neccesary for this exam. Have you looked at the exam topics, http://cisco.com/web/learning/le3/current_exams/642-901.html
I took the BSCI last year and failed it the first time I took it. Don't do what I did and briefly study the Multicast and IPv6 sections lightly....study those topics like you would the rest. Good Luck