Fetenawen yemeyawetut are your teachers adel..so the first main study material should be your exercise book...secondly use the text books...it will help you on things that are clearly stated on your extercise book...do the revision questions on the text book...and watch videos or google any topics that confused you... and if you want to go further, you can do practice questions on different other books (like extreme series)....everything you need is in front of you...you just have to know how to use them...you don't need any telegram channel or group