I attempted IPH thrice because I love India and History of India.I have been reading about it eve since my childhood as my father and grand father would tech history.Yet,I got a depressing low score of 51 and 60 in CE 2011 and 63 and 69 in CE 2012 which of course was better.
IH is better because history and trend of marking bears testimony that IH has always brought good marks than IPH.It is also lengthier like IPH but I found it more interesting and perhaps glamorous than IPH.In last three years you would find countless people having scored more than 145 in IH;but IPH has remained dry in this regard.
Whatever the subject you choose,please make sure that you study thoroughly from foreign authors.
To have good marks in history,either it be Indian or Islamic,you shall have to establish a romance and a love with subject instead of taking it as a burden.
I again assert that Islamic history weighs far heavier than Indian in the balance of marks.

pscychology

Which books will you recommend for the peparation of IH?

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“Too many of us are not living our dreams because we are living our fears.”

I would suggest to prefer IH as I have also studied IPH that's why I know the difference b/w both. No doubt IPH is akin to PA but then what, it will fetch you low score. Can you afford to have low score in paper2 of IPH as well as PA.
Yes, if you have command over IPH then go for it.

Am going to opt psychology, journalism, sociology, and IH.. So what you say about the combination..? Are these scoring subjects?

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“Too many of us are not living our dreams because we are living our fears.”

i choose IPH,ECONOMICS, POLITICAL SCIENCE, is these subjects r scoring r not????????????

For Indo Pak 1,
Have K.Ali as your syllabus book.But K.Ali is not enough at all to fetch good marks.So you must have ,

History of Medieval India by Stanely Lanepool.
History of India (Perhaps Oxford History) by Vincent A Smith

For Mughal Period and post Mughal period,you may have,

History of India by Vidyadhar Mahajan

For Indo Pak 2
K.Ali and Ikram Rabbani's book shall be your syllabus books,and you shall have to prepare notes from K.K Aziz,S.M.Ikram and I.H.Qureshi's books.

If you have penchant for reading then following books shall immensely help you in IPH and PA and you shall thoroughly enjoy them; else the aforementioned books shall suffice.

The Sole Spokesman by Dr.Ayesha Jalal
Jinnah,India,Independence,Partition by Jaswant Singh
The Indus Saga by Aitazaz Ahsan
Freedom at Midnight by Dominique Lappiere

IPH shall consume two months at the most for satisfactory preparation.You shall have to copy quotes,analysis and events from other books which are missing in K.Ali books.Do not forget to prepare MCQs from last ten year papers.