One of my friends was selected for BA French at JNU a few years back and here are his tips on how to do well in the entrance exam. 

G.K: You should incorporate every little detail from Arts, Literature, Drama, Culture, Dress, Cuisines, Geography, Nobel Laureates, and more to become familiar with the language you have pursued.

Reasoning Skills: You should be proficient in solving several coding-decoding problems, especially alphabetical orders, blood relations, syllogisms, direction, and ranking tests.

English: It is equally important to be as strong in English as you are in other subjects. Various course areas, like the Basic grammatical Rules, Vocabularies, Reading Comprehension, and Passages should be on the tip of your tongue. For best results, you should follow the editorial and articles published in “The Hindu.” 

English includes a major marking scheme for all the other sections. Now, since an essay alone contains a scheme of about 20-30 marks, it is best that you practice writing ingeniously without using heavy vocabulary. JNU appreciates the artistry of innovation and it is best to keep their tastes intact. Simplicity is encouraged along the lines of critical thinking, at least more than sophisticated word formations. 

It is best to keep your thoughts perfectly aligned with the subject area, and not outside of it.