I am planning on building a ground level deck over an existing concrete patio, and am not sure where to begin. I am wondering what the best foundation would be for the deck. I found an article that suggested using a wall frame type set-up but wasn't sure if there was another route I should take, and whether I should secure the wood to the concrete or let it "float" on top of the concrete.

If anyone has any ideas please let me know.

Thanks

The best foundation should be the patio itself. I don't see why you would need to dig for posts. The weight of the deck will be dispersed along the patio itself.

If you do that try to put pressure treated 2x4's flat on the slab and build off those. You can secure the 2x's to the slab with tapcon screws so they don't move around when your building on them. These will be run perpendicular to the main joists. Maybe install them every 4'. (dont know the deck dimensions)
That way water won't get trapped along the joist under the deck and air can also flow under the deck to keep things dry.