Excellent question.
I’ve found that a blend of these two works best:
-Networking (advisors, consultants, senior executives, etc.). It allows you to get in front of the people you’ll inevitably deal with when and if something comes up. Advisors are always looking to make something happen, thus making your interest known is helpful.
-Industry research (identifying leading players in the niche you’re targeting)
Depending on the acquirer’s size and leadership in the sector/sub-sector, often times targets approach directly/through their advisers.