What is the starting point for implementing Single Sign On?
Ok. So obviously I was kidding and before the sales guys ask to have me removed from the community, I'll try to give some serious advice.
Read. Read as much of the planning docs as you can get your hands on. A ton of planning now will save you so many headaches in the future. Start with implementation doc and go from there.
Some points that I believe are important. Figure out where on your network your policy servers are going to be. Then the policy store and user store. Any issues with them talking to each other? Don't start out of the gate with network problems that will take a total reconfigure of your network to implement. Same goes for web agents. All these things need to talk to each other with the policy server in the middle of the action.
Grab a couple of servers and install everything you think you'll need and play with it. Nothing is a great teacher like experience and mistakes.
Ask questions. This community is here to help. You have a wealth of knowledge and at least for me, bad practices that we can warn you about.
Thank you. That's help full.
Also, if you haven't already done, consider doing some structured courses on SiteMinder.
There are various level of course depending on your expertise.
It starts with Level 200 and goes upto 400.