During the sales call, the focus should be on the value of your services

I deal with this pretty frequently. I've learned that if the prospective company has their web developer/designer in on the conversation, you'll want to be more careful. That person is likely familiar with most of the concepts you'll be discussing. If you're dealing with the execs or marketing team, you can let your guard down (while still not giving away specifics).

During the sales call, the focus should be on the value of your services, and less on the strategy for success. I usually don't mind giving a couple of tips, but you can usually tell when they're culling for information because the questions are less about your services and more about what you recommend. At this point I usually offer an SEO playbook that includes page specific recommendations that their team can implement, for a fee.

I also make a point of talking about both the the hazards of SEO (drawing irrelevant traffic, getting delisted, etc), and the number of tools involved. I don't mention specific products, but point out that we have tools for keyword research, reporting, analytics, conversion optimization, click paths, etc, and that we draw on all of this information to bring them targeted traffic.

SEO isn't difficult and there are no secrets, but it is work. Most SEOs that I know LOVE educating people on how to achieve success, but we have to make a living, too.