In this XCOM 2 guide, I'm going to go over a streamlined build order for the Avenger that should suit your playstyle and goals for the WotC campaign. But it's worth keeping in mind that the first several structures you work toward will set the tone for your whole campaign. Despite every structure being important, I'm a huge proponent of the idea that you can make nearly any build order work. While I don't believe there is a truly incorrect method in how you start building, there are certainly some strategies that are more useful than others.