The art of building is easily underestimated, however it is of great value for the team. To help new builders here are some tips:
1. Don't build until you have observed a few games, either by spectating or by participating. Take notice of how the game flows, of the camping, of the raids, or the sieges. Take notice of how aliens don't put all their eggs in one basket, but humans lean towards big central bases.
2. Repair and rebuild. Humans can repair buildings with the right mouse key (alien buildings repair themselves). By repairing damaged buildings and rebuilding them if destroyed you can make the base last much longer. Enemies often attack and retreat, hoping to come back and finish the job. Make sure their work was in vain. Note that repairing and rebuilding is something you can do even when it's your first game, you are after all not modifying but only sustaining.
3. Start small. It's best to start out by putting up a few turrets/tubes. Keep an eye on them and notice how well they do, or not.
4. Be careful around vital buildings. You should only ever delete/move those after consulting with the team (use 'y' for starting a teamchat message).
5. A defense near the reactor/overmind can be very effective. Outer defenses get breached. In such a case a single turret/tube near the most vital building can make the difference between defeat and prolonged survival.
6. Don't duplicate. A human base very rarely needs two armories and medpads. It very rarely needs three spawns. By duplicating such buildings you are taking points away from more useful stuff. Be aware though that there are situations when this rule certainly doesn't apply.
7. Communicate. The strongest team fails when it doesn't act like a team. A team can defy unsurmountable odds when all of it's members work together for the whole. I've been in games where the builders didn't communicate and instead were constantly undoing eachothers work. Avoid that, communicate. Also when you're doing something somebody else asked use three keys: y, k, return (sends "k" over teamchat).
8. Be flexible. No strategy will always work. A base relocation to the elevator room on karith may seem a good idea, but it could easily be your Waterloo. Moving your base forward can help in some maps (uncreation for example), but it can also be a very bad idea. Look at how the opponent attacks/defends and plan accordingly.
