How to fill UPSC Civil Services Answer Sheet correctly

What Is the Correct method/Do's of filling UPSC Civil Services Answer Sheet

UPSC has released the correct method/do's of filling the answer sheets.

Correct Method/Do's to follow for filling UPSC Civil Services Answer Sheets

The Intention behind providing these model instructions by UPSC are that: 

The Candidates should avoid mistakes while answering the exam which will reduce there chances of selection

How to avoid mistakes in UPSC Civil Service Answer sheet?

Check Common Mistakes/ Don'ts to avoid by candidates in Descriptive Papers