Wat u could do is that practise using rd , rs and even the ncert is tough enough
had that same problem some time ago , but now its all sorted out ..
1) you first gotta aim at wat u wanna prove
if you have angles in it , name them as angle 1, 2,3 ; trust me thats gonna help you
TIP - never ever find logic in these questions cause there isn't
2) then the second step would be using all the properties you know , e.g. angle sum property , exterior angle , wateva it is
then form some equations using them
3) then either you have to equate them , add/subtract them or put the value of one equation into another.
these are the three common methods of the "proving" questions
follow these and its not gonna be a problem for u