How to design a form with more than 30 mandatory field inputs

I need to solve a situation where I have to design forms with 30-40 input fields (most of them are required) in order to complete the task and generate a final output. With th design principle "Minimum interaction, maximum output" Following approach I am thinking to handle this situation:

  1. Implement predictive search option where ever field require
  2. Split the 40 fields in logical grouping page and allow user to submit form in progressive closure way
  3. Use conditional logic to shorten forms
  4. carefully use the list, radio button, checkboxes and dropdown
  5. Use the visual cues and icons to make form field more intuitive

Can you suggest me any other way to handle this situation in better way. Note 40 fields is on single product and 25 different product have similar kind of mandatory field to fill to accomplish task. Please suggest any different perspective.