How do consultants ask questions to gain knowledge about the clients way of working, industry, etc? Are there any practical books, methods and techniques or websites on this subject?

You ask them what you want to know...?

Nah! Surely....1. Decide which answers provide your firm with the best follow on sales opportunities.2. Ask junior client people how their business could be improved3. Nod wisely as the talk, while thinking about your fantasy football team ( or suitable alternative)4. Submit output from point 1. to client senior management

Ha!Coolio - you forgot to add number 2 does come up with a lot of good ideas that client Senior Mangt look at say "great idea! We should be doing that asap, thanks for working that out for us"

Spot on :)