Post Terran tips here
Vision is a recourse in Star Craft 2, don't just clump all of your supply depots together in one spot right off the bat. Start out by spreading them around the perimeter of your base. That way you can see drops/reapers/ blink stalkers coming while looking at the mini map.
never thought about that seems smart, also a good strategy is to harass mineral lines with hellion drops, or marine and marauder drops so your opponet does not get to far ahead of you in resources