Expand expand expand

I have played quite a few games where my opponent did not expand at all.  I crushed him easily.  When you expand you can double your resource collection rate and therefore double your army.  I expand to at least 2 or 3 expansions in any of my games. Some of my opponents who did not expand where making units very slowly and only a few production building. I on the other hand had 3 barracks, 2 factories, and 3 starports. I was able to create a large sized army in a matter of 2 minutes. He had a few marines an marauders while I had some siege tanks, some upgraded marines and marauders, and some banshees.  I destroyed him easily. That is why you should always be looking to expand.