Build or wait, a matter of research
 

How do you handle building the more mineral intensive facilities. Do you build the level one, the upgrade to level two, then upgrade to level 3 as you get each tech? Or do you concentrate on that single tech and wait until level 3 buildings are available, then build from scratch.

Which brings up the other part. In what manner do you research? take a single tech line and run it out, ignoring the other branches, or pick up the cheapies with the change from you primary research choice. IE. tech-a, lev2: you have 30/50k done and producing 30k, do you let the extra 10 go to tech-a level 3 (say 200k cost). or pick up those 5k and 5k cheapies with the surplus.

Re: Build or wait, a matter of research
 

It depends on what the facility is, and how long it will take to get the next level. If you hit the upgrade all button, it upgrades all facilities that are in the queue. So, you can put them on hold for a turn or two at 1 turn left waiting on a tech level, and then save the upgrade costs. http://forum.shrapnelgames.com/images/icons/icon10.gif

Research path is entirely dependant on the game settings and conditions.