As low-level decks seem to be a constant subject of interest, I thought this was worth sharing as a slightly different situation.
We needed an elevated entry to a new door into our house from the driveway. Being a very level block and having high rainfall, it had to provide a dry entry. There is a very small amount of slope in the area so the gravel ensures water can easily flow.
I wanted the deck to be at the same level as where the first step tread should be on the stringers. That meant I needed to install the first step tread upside down, i.e. underneath.
Due to its position beside the drive, in an area that is used for three-point turns, I didn't want to put the edge of the deck right on the edge of the drive. I suspected it would be reversed into, hence the setback.
Here I have the external frame and posts in.
Then I cleared away soil beneath the frame.
Lay the drainage mat and add gravel before finishing the frame. It's much easier that way. If you don't add a drainage mat, then over time the gravel will sink into the soil.
For the main supports, I used stirrups in concrete. I used centre-fix stirrups, and here's a very rudimentary diagram of how I fixed them in. The holes were only around 300 to 400mm wide and around 400mm deep. Our soil is quite stable, so I didn't need to go much larger. Each took about 1½ bags of quickset concrete.
As it's a level area, the concrete really just becomes a stabilising deadweight. It's not a structural footing as it's not taking a major load or on a slope. I feel confident using these smaller footings, as I've switched to using a high MPa concrete mix. It doesn't crack or crumble like the lower grade stuff.
For the secondary supports, I used TuffBlocks as the gravel gave a perfect base.
Next, I put the drainage gravel in.
Here the Merbau decking is laid. I used 140mm boards. This is same size as the bearers so they can also be used to conceal them on exposed faces. Then I put down another layer of drainage mat onto the drainage gravel around edges and then dressed it with river pebbles. The lowest point of clearance above the finished gravel was about 50mm and there was around 40mm or so of gravel above the soil.
Adam posted more helpful information in the comprehensive guide How to build a low-level deck, which includes handy pointers on the pitfalls to avoid, what materials you could choose and how to achieve the best drainage.