First lines are just as important in a non-fiction as they are in fiction. To learn how to do this, simply read through books that you own to see how other authors have done this.
Your attention grabbing headline could be a question or a statement.
In Now, discover your strengths, Marcus Buckingham uses this method, in some but not all of his chapters:-
What does a strong life look like?
What can we learn about strengths from Colin Powell?
In People Styles At Work, Bolton and Bolton make bold statements:-
No wonder we have people problems.
As long as you live, you will have at least some unwelcome and unproductive friction with others.
People are more predictable than you think.
Ever been baffled by someone’s reaction to something you’ve said or done? Join the club.
In Molecules of Emotion, Candice Pert, uses her opening lines (in my opinion to great effect).
Looking back over the last 25 years, it seems that destiny played an important role in the unfolding events that led to the discovery of the elusive opiate receptor.
I look up from my lectern out into the darkened auditorium, where my audience, barely visible, awaits my further words.
Go back through your book and craft your first lines, do a question and statement for every chapter, leave them and reflect on which has the most impact.
This exercise has been taken from Edit your non fiction book to sell.