Well, I cracked the neet this year without coaching and that too in just 4 months so maybe I am eligible to answer your question. I have secured 3019 rank in neet 2018. Not great but enough to land me in most prestigious college.
But I was the student of Aakash 2 year medical program during 11th and 12th so my basics and concepts were cleared already and I had work very hard last year. (Last year i.e in 2017 my rank was around 13,000 . You also need luck for competitive exams)
Now for self-study, you need to do the following things
- Take dlp of any reputed coaching. Plan your timetable according to their materials. Try to complete one set before they give you another.
- Take offline test series of the same institute. This will help you to cover the syllabus on time.