Hi u may have just strtd ur prep so u may find rsm difficult so it is better that u do some basic books like NCERT H CV R C MUKHERJEE or BAHADUR ML KHANNA etc. first for theory and practice then u can shift on to rsm it may take some time for u to adjust and remember IIT JEE tests ur understanding of concepts so any one(i.e rsm of Brlliants is good enough)........