Supreme Commander's tutorial suggests that you begin by building 2-3 Mass Extractors followed by 2-3 Power Generators and your first factory. Both Eschez and Basic stick to this preliminary build fairly closely.However, unlike the example in the tutorial, it's important to note that both players begin with two Power Generators instead of Mass Extractors. Tapping out your resources will slow your production rate to a crawl, and while they're both important, Power is slightly harder to come by than Mass. So it makes sense that both players begin this way.
Note that both players make full use of the shift-click command. Hold down shift and assign multiple build and movement orders to your units so you don't lose a second of efficiency while moving on to another task.
Also, both players begin pumping out a mixture of engineers and Tech 1 land units from the get go. This allows Eschez and Basic to expand their economy with additional Mass Extractors and Power Generators while scouting out each other's positions.