When a given condition is very general, like

x is an integer,

x is a positive number,

then it's time to check various conditions (mostly fractions/decimals between 0 and 1).

​

Or when nothing is mentioned about a variable, be alert.

I always go "red alert" mode when given information is general in DS.

Putting yourself in this awareness mode will be the first step to reducing mistakes in the DS.

​

Also, I always double check with asking myself if there are multiple possibilities to the answer. If there are multiple answers possible, then it is NOT sufficient.

Sometimes I confuse with answering "no" as not sufficient, which is not true, I consciously check if multiple answers are possible. (If you are able to answer no, then you can answer definitely so it's sufficient)

Hope that helps!