I have to admit that I may not be able to guide you regarding preparation of all optional subjects, naturally.
I faced the question as to what my optionals were?
My optionals were Law and Literature of Gujarati Language.
My medium for Main and Interview was English.
I should, to begin with, point out books for Law Optional for the benefit of those who dares to opt Law.
+Constitutional Law : Bare Act, Guide for LL.B. Exam, M.P. Jain or any other book as Reference only;
+IPC : Ratanlal & Dhirajlal, Bare Act and Guide for LL.B. Exam;
+Law of Torts : Dr. R. K. Bangia;
+Mercantile Law : Avtar Singh, Bare Acts and Guide for LL.B. Exam;
+International Law : S.K. Kapoor or M.P. Tandon;
+Contemporary Legal Development : Bare Acts, Guide for LL.B. Exam, Internet Material;
+Minor Acts : Bare Acts, Guide for LL.B. Exam;
One must practice regularly to write answers because in Law it is not lack of knowledge but lack of practice which is responsible for poor score. Apart from ample writing practice a candidate should also be aware of direct, to the point, relevant and complete answer writing.
This should be considered as a general guideline, which is subject to modification from individual perspective. Should there be any specific query, comment can be a helpful tool to ask briefly.