Preparation for the IISER Aptitude test will not ask for anything more than your preparation of Boards. The syllabus includes all that you studied in class 11 and 12 and for exams like JEE (mains and advanced), AIPMT, NEST. You need to keep some pointers in mind while you plan out your strategy of preparation. 

• Study Theory: You need to be very clear with all the basics in your syllabus. It is of no use to mug up all the high-level books like H C Verma and alike. Just stick to your NCERT books. 
• Once you are clear with the theory of the concepts from your NCERT books, you can look for other reference materials, notes from teachers to brush up on particular sub-topics that you need to be more sure of. You can also make your own notes since writing helps you remember things better and they can serve well in the end for revision purposes.
• When it comes to Mathematics, you can never be prepared enough or solve just the right number of problems. So, make sure to practice as much as you can since that will help you find various techniques to come up with solutions and faster of course. 

Hence, in general study and practice all the subjects- Physics, Chemistry, Mathematics, Biology and be thorough. It is okay if you did not have either Maths or Biology- don't attempt the questions you are not sure of, that will lead to negative marking. You will need to get more than 35 questions correct out of 60 in order to secure a seat at the institute. 

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. 

My brother studied M.Phil in Forensic Psychology from Gujarat Forensic Sciences University. He took the online entrance exam for NFSU in 2020 during the first wave of Covid-19. Here are his tips on how to do well in the entrance exam. 

• Be aware of the admission notification. Keep checking. Go through the eligibility criteria for your course. Make note of the last date of application and complete your application requisites before that.
• The syllabus changes each year. So, check it thoroughly. In 2020 the syllabus of Masters was General Psychology, English language, GK, and Research Methodology. In 2021, it is General Psychology, Research Methodology, and Statistics.
• Stick to the material available for study. Always begin with the fundamentals.
• Since there is no negative marking you can attempt all the questions to increase possibilities of selection. 
• The interviewers need to see that you are focused and motivated. If you are going for a research-based program like M.Phil, P.hD., etc. then make sure you have ample research experience in hand like the dissertation of your Master's course.

The entrance is competitive and not difficult. You'll find only a few tricky questions in there. Most of the questions are of average difficulty. With strategic preparation, you can easily score well on the entrance test.

The pattern usually followed in JIPMER is quite different from what is generally seen in NEET or AIIMS. Prior to taking the exam, you should become acquainted with the pattern of the exam. 

Examination Pattern: 

The total mark for the examination is 200. Now, every question carries one mark. There is negative marking so, it is best to attempt questions that you are sure of. Moreover, the exam is conducted on an online basis with about 150 minutes allotted for it in total.

Book Recommendation: 

Here are some recommendations you should know, as per following a book. 

• 16 years of JIPMER exam solved papers by Arihant. It can help you in understanding the concepts of the questions
• NCERT Text Books.
• It is best to follow D.C.Pandey Objective Physics for Medical Entrance, for physics.
• R.C. Mukherjee is best for the Physical section of Chemistry.
• For organic chemistry, you can follow O.P. Tandon
• For inorganic, you should be extremely familiar with NCERT itself.
• For Biology, Trueman's Publication is one of the best choices.
• It is advised that you solve as many MCQS as you possibly can. For similar purposes, you can follow MTG Biology as well.

Solving a total of 200 questions within almost 150 minutes is unbelievably difficult, yet with practice, it is quite probable that you can ace it. For similar issues, it is best to solve Biology in the first go, while keeping English as the second option. Following both, you should complete Chemistry and physics. The last section you should take hold of should be Logical Reasoning. 

Prior to the exam, you can take a mock test. It can help you get familiar with the exam pattern. Most essentially, you will be provided with a virtual calculator to attempt every question.

Now, to reserve a seat, you must be in the top 100 since there are only 200 seats. A decent score of 180+ can help you secure a seat. 

Firstly, you should know that EKT is conducted by the Indian Air Force (IAF) for the technical groundwork and it is an online computer-based exam. The notification for this year has been released and the exam will be conducted between 20-22 February 2021 for both exams. You might want to note these down as well-

• If you are applying for the EKT AFCAT Ground Duty (Technical Branch) post, you must attempt both technical & non-technical papers.
• Know the Syllabus and Exam pattern to prepare thoroughly.
• In the non-technical paper, G.K. will be a decisive factor, so focus on that and acquire the latest and important information from newspapers. The reasoning section will be easy to clear if you've practiced enough. You just need to chisel your logical and analytical skills.
• You should understand concepts with total clarity, be clear on your Engineering subjects. Testbook has a good set of resources available. You can download and solve the complete mock test sets to be efficient and refer to books and videos through the website.
• Make a schedule and follow it without distractions. 
• It is advisable to download the previous year’s question papers from the official website of EKT AFCAT and solve those at least 2-3 in a sitting, it will give you a good idea on the type of questions asked and the subtle intricacies with which to attempt them.

There are some books you can refer to for preparation: For the non-technical paper- Lucent's GK; RS Agarwal's Modern Approach to Verbal and Non-verbal Reasoning; and MK Pandey's Analytical Reasoning can be referred to. 

For technical, you can read the Objective General Engineering by GK Publisher's; Let's Crack EKT by Shourya Publications; and AFCAT by Arihant. 

I hope this all will help you with your preparations. Be updated and enjoy the process.