Tips w1.For Non IT Student they should first complete computer hardware and computer software. if you do this will improve your confidence and remove your fear regarding computing and informatics.
2. If we look at last two to three year question paper we see that Binary conversion and Logic Gates are compulsory question so make strong command over this.
3. To complete computer theory in better way , I would like to advice you to use PETER NORTON textbook of TATAMcGRAW HILL publication. this is the Best book for computer theory i ever known. i used the same book and cleared my computing and informatics paper.
4. For Programming Language i want to i want to say that first make strong command over C Language after that learn C++. If you have any friend having IT background take his help otherwise join any institute for coaching of C and c++ language.
5.If we look at past few year question paper we find that Networking question asked regularly so networking question may be your sure marks if you prepare for it in good way.