I say sort-of, because if you read the articles that was linked by Andrew, it's quite obvious that I didn't understand some pretty basic concepts very well. For instance, the depth buffer. That forced me to rethink my design a bit, and how I process the content for drawing. It also forced me to do some math, and I realised that for items like the palm tree, it might just be possible to model it completely instead of using very few faces with alpha blending. And as a result it actually looks better.
Apart from the above, I've managed to get somewhere with one of the enemy units as well. A simple recon vehicle. Here is a render of it. There's still a bit to do before I can use it as a game model, one of which is the texture coordinate unwrapping, which will probably prove to be a pain.
You might have noticed that there is a rather complete lack of concept art so far. The fact of the matter is, I just don't have the time to sit and churn out pencil sketches or otherwise to design the game elements. However, as things start ramping up, I'm pretty sure I will have to take a step back and spend some time on this.