Frankly, the preparation tips for the IIM Indore IPM Aptitude test and personal interview are best understood from a student who's been through the process recently, not a coaching instructor or institute.
The aptitude test to interview score ratio is 60:40. The study material for the course can't really help you much. Sharpen your math skills if they are lacking. It's a must because quant is a stress if your math skills aren't up to par. The computer provides you with a calculator, but it can only perform basic addition and subtraction. If you are proficient in English, verbal is simple. No point in opening the dictionary to figure out new words or trying to mug them up. Read the papers and any classic literature you can get your hands on. The rest would probably work out. The majority of the reading was at the CBSE level. Your reading speed is the only potential stumbling block. Reading newspapers will also help you if you are chosen for the interview. The term "electronic commerce" refers to the sale of electronic goods. Also, the break between the test and interview is a good time to brush up on your class 12 syllabus.
The one thing to remember is to never lie. They'll see right through you, and trouble may be on the way. Presentation is essential. Don't be scared to ask for a little time to ponder upon a question, but don't be overconfident.
The key is self-assurance. After all, the panelists and the test are only attempting to assess the breadth of your knowledge, your self-awareness, and the goals you wish to achieve. Don't compare yourself with others or think of the multitude of kids trying their luck too. You will succeed there if you are aware that IIM IPM is where your heart truly lies.