40% of reading comp questions are 'inference' and so it's pretty important to have good skills for this.
The very name 'inference' is completely misleading.
Make no attempt to infer anything. That will lead you to subjective answers, probably incorrect.
Consider: How people infer results, is to a degree dependent on their cultural background. Yet the GMAT is supposedly international. What can you infer from this?
What I am about to say is counter-intuitive, but true. I've tested it with my students.
Read the question and quite simply look in the text for synonyms of key answer words and phrases.
EG: . . . . . . Lady Charteuse lay back on the chaise-longue, and yawned. The gas mantles were turned up too high again. Really, the quality of servants these days! Where the devil could Clarence be? She was hardly able to keep her eyes open.
A . . .
B . . .
C Lady Charteuse had taken sleeping pills.
D Clarence is one of the house servants and is responsible for the gas lamps.
E A chaise-longue is a comfortable chair-bed popularised in the Victorian era.
This is just a crude example I dreamed up to illustrate my point. The correct answer, E, mentions the chaise-longue, and 'chair-bed' is associated with 'lay back', 'yawned', 'hardly keep her eyes open'.
Don't infer. Just look for equivalents. That's it.