Is there any guideline or steps on how to create an effective work instructions for manufacturing company?

I've seen a number of expensive "Guide to Writing [Whatever]" books on the market, but when I'm trying to determine what a (potential) client wants, I download some of their recent documentation/user guides and look those over. Then I download some of the competition's documentation, and compare it. Then I incorporate the best features of both in my proposal, along with some high-quality samples of graphics and "exploded views.

I don't know if you're still at the proposal stage or are ready to write, but there's no need to re-invent the proverbial wheel! You may utilize existing and effective structure freely.