Law

Hi buddy,
You can apply for the same only when you will be in the final year or after clearing LL.B. If you are so much desperate to appear the exam you should start your full-fledged preparation now so that you could qualify the exam as early as possible. PCS exams need very determined preparation and it ideally takes 2 years preparation at least. So, start your preparation now. You should go ahead by starting from general studies and when after sometime start the optional subjects and remaining papers. There are certain universities offering three year LL.B. Course after graduation, topmost being Delhi University (DULLB entrance):
Mumbai University MHCET Law entrance)
Banaras Hindu University (BHU law entrance)
Panjab University (PU law entrance)
O. P. Jindal Global Law School (ISAT)
Symbiosis University (Set law through which after filling form one has to go for WA PI as there is no entrance exam for 3 year law). All the universities have their separate exams. Mostly, you need to focus on static and current gk for which you can buy this book called 'Lucents General knowledge'. As regards legal reasoning and knowledge is concerned, you can buy either of the two books named 'Universal guide to LL.B. Entrance' and 'S. Guide to LL.B. Entrance'. These two books cover your basic legal, logical reasoning and English part. Both English and LR are not of much weightage in LL.B. Entrances, neither is maths. Some exams don't even have maths. I suggest you go through these two books thoroughly and you can also join any test series which are offered by various institutions across India. That will help you practice.

There is nothing like best books for CLAT. There are good books which help in preparation. First I would recommend you the books which are widely used for this exam and then I will give my strategy/preparation tips. A) English - Word Power Made Easy (Vocabulary), Any RC booklet, Grammar rules can be done through videos available online/coaching classes (there are books like Wren and Martin also), idioms and phrases can be done from the numerous sources available on the internet. B) Mathematics - Quicker Maths by M. Tyra, Quantitative aptitude by RS Aggarwal
c) Legal Aptitude - Universals guide to CLAT and LL.B. Pearson CLAT Guide by Gargani et cetera
d) Logical Reasoning - MK Pandey for verbal reasoning, RS Aggarwal
e) GK - For static, people refer Arihants guide.