Hi ! I have cracked NEET in my first attempt so I think I am eligible to answer your question.
I scored 654/720 in NEET 2017. It is not impossible to crack NEET in your first attempt. The only thing you need is to do is parctice and a proper understanding of the concepts.
Practice physics everyday. Practice the previous year questions. Practice the important topics like mechanics , work and energy, properties of bulk matter, electricity, magnetism and optics. Then practice the remaining topics.
For chemistry, you need to read inorganic almost everyday even if its only for half an hour. Practice the mechanisms of the organic reactions. For inorganic practice the important topics like p block. For organic ,general organic chemistry, aldehydes, carboxylic acids,ketones,alcohol,amines. For physical chemistry thermodynamics, equilibrium, structure of atom, electrochemistry and chemical kinetics.
For bio read the human systems, evolution, morphology of plants, photosynthesis, respiration in plants, plant growth, ecology and genetics.
Practice from standard practice books like MTG or Arihant. Keep the track of time when you practice.
Clear your doubts regularly. Don’t keep piling up your topics. Don’t mug up the chapters instead focus on solving the problems.