A Search Engine Land post discusses why it's useful to share SEO tactics with your clients. It's not about holding "intellectual property" to yourself. It's about empowering the client. And there's no harm in it. Here's why.
For one thing, even if you provide information to your clients, SEO is constantly evolving so it will still be your responsibility to keep up the pace. But still, there's a benefit of knowledge transfer. With the constant changes in the industry, "[a]ctive clients can provide additional eyes and ears to industry changes and trends, as well as practical insights into the effectiveness of advanced SEO tactics."
Additionally, the article argues that there should be a documented methodology:
The client should also learn the philosophies and processes behind keyword research, page selection, content development and optimization, link building, and social media marketing.
By acting on the Diagnostic Audit findings, the client can identify obstacles that are hindering their efforts to achieve top search rankings.
Finally, it is also of critical importance to understand the value of analytics. With the right training, your clients can understand the complexity of analytics applications.
The discussion evolves on Sphinn where many SEOs believe that the mutual relationship is important. As one person puts it, "Education is a bigger part of my job than the actual process itself."
It's important to acknowledge that there are some SEO firms that are just very open with their processes. So most people agree that there's no reason to hide anything from your clients.
Forum discussion continues at Sphinn.