You can start your preparation by studying basic class 12 books. Also refer to the other books which you might have studied in class 12. Go through the major current affairs and the static GK. Read newspapers regularly for current affairs. You should have sufficient knowledge of those subjects which you're going to take as your subject combination in BA. That will be all for you to crack the paper.
You can also purchase the books like-
Lucent's General Knowledge
Arihant's reasoning book
Hope this helps. All the best.