Define your target
A crucial part of USMLE steps is the target score you want to achieve.
You should decide it on the factors some of which are the specialty you want to get a residency in, how early/late after the MBBS you want to start the residency, what college you want to target for residency, the contacts you have in US and some others.
Decide the time of exam
There are usually one of the two time periods when people give step 1
End of third year/starting of final year.
After Internship.
In the case that you want to score as high as possible and have no defined target score, the best time is to give the exam in a few months after completing internship, however, you must start your preparation from now itself.
However, if your target score is defined, is not too high or is easily achievable by you, you should give the exam at the end of 3rd year/start of 4th year, but also only if you are achieving your target score in mock exams(NBMEs) by the end of of your preparation/ nearing your exam date, if not, you have to take the decision if the score you are getting is acceptable for you or you have to postpone the exam.
Decide the study material
Check this answer for material of each subject.
Source: Quora Digest
Define your target
A crucial part of USMLE steps is the target score you want to achieve.
You should decide it on the factors some of which are the specialty you want to get a residency in, how early/late after the MBBS you want to start the residency, what college you want to target for residency, the contacts you have in US and some others.
Decide the time of exam
There are usually one of the two time periods when people give step 1
End of third year/starting of final year.
After Internship.
In the case that you want to score as high as possible and have no defined target score, the best time is to give the exam in a few months after completing internship, however, you must start your preparation from now itself.
However, if your target score is defined, is not too high or is easily achievable by you, you should give the exam at the end of 3rd year/start of 4th year, but also only if you are achieving your target score in mock exams(NBMEs) by the end of of your preparation/ nearing your exam date, if not, you have to take the decision if the score you are getting is acceptable for you or you have to postpone the exam.
Decide the study material
Check this answer for material of each subject.
Durgesh Agrawal's answer to What are the best resources for the step 1 USMLE for each subject?
How to start preparation
In my experience and opinion on basis of my own preparation and of many others I have closely seen, the best is to start by doing Firstaid and a question bank, preferably Usmle Rx, together, which takes about 2–3 months, depending on your speed.
After this give an NBME exam.
The next should be doing Firstaid again, but this time with UWorld, which is the question bank most similar to the real exam.
Give an NBME again.
Now that you have done two question banks and first aid two times, and also given two NBMEs, you can assess where you stand in your preparation, what areas are weak and on that basis decide what other study material to use and how to further your preparation from that point.
Keep in mind that upto this point only you would have taken 4–6 months atleast.
after this it is
Give NBME ——-> assess weak areas ——-> read them ——→ give NBME again and repeat till you get your target score.
Also you should keep atleast 15–20 days after you achieve your target in NBME and exam date so you can revise and gather all your preparation together.
Remember Step 1 is only a very small part of the very long journey which is getting a residency.