I've just got one, a hand circular saw, and never used one before.
I read all the manual, yes I read it.

And the most important safety and usage points about this specific (hold it) I read were:
- Always hold the saw with two hands
- Don't be inline with the saw
- Don't change body position during the cut.
- Never use your hands to hold the cutting panel.
- Use the wider side of the support shoe on the holding piece.

Now, watch this guy in a dewalt commercial, he switches position and kept that ackward position through all the cut:
http://www.youtube.com/watch?v=44gRuA7yGak

This guy showing how to make a jig, uses the wider side of the shoe on the cutting side holding it by hand, it cuts from right to left and to left to right interchangable:
http://www.youtube.com/watch?v=CH5dW-QcgeI

This "expert", show how to do it, adn though he never turns it on, he is using the wider side on the falling piece:
http://www.youtube.com/watch?v=WFCJ-1rpuYs&NR=1

So, I'm concluding 4 things:
- You can only follow all manual rules with short cuts because all the length you have available is of your arms and the bend of your back.
- For long cuts, in order to follow the manual rules, you'd have to use it left handed.
- Nobody is holding the cutting piece or they're end up holding it with the hands.

So? What's the correct way?