Decks, Patios, Porches and Docks - Installing new wood deck over exist. concrete patio

I have some friends that would like to pay me to install a new wooden deck over their existing concrete patio (which slopes away from the house for water runoff). The concrete patio is two tiered: the first section is about 6.5" below the level of the interior floor, and the second level is about another 6" below that. The wooden deck would be one continuous level over both tiers. Is there some building plans or techniques you can point me to that describe how to build a wooden deck over a concrete patio? All the material I've read so far just talks about building a deck from scratch over bare ground, and digging footings, etc. which I won't be doing.