In StarCraft: Remastered, Terrans can be tough to play because of their initial combat unit, the Marine. It's softer than the Protoss Zealot but more expensive and time-consuming to produce than the Zergling. This means that if you aren’t careful, you can be taken down in the first ten minutes if you don’t get the right defenses up.
Starting out tips for Terrans
Your best beginning strategy is to max out your SCVs so that every mineral deposit has a dedicated worker. Then build a Supply Depot near your base’s entrance to start forming a wall. Then build a Barracks, the complete the wall in front of your base with another Supply Depot, and then an Engineering Bay in between them.
This wall will keep your enemies out while allowing you to stack marines behind it and take them down. When you want to send your army out, you can just lift off the Engineering Bay and set it back down once they’re off. Just make sure that you keep an SCV nearby to repair the building as needed.
Medic and Marine combo
One of the most basic strategies for Terran players, and one of the earliest you can put in play is to do the above steps and then build an Academy and another Barracks. Research Stim Paks at the Academy and start churning out Marines and Medics.
Try to have one Medic for every three or so Marines and once they’re in range of your enemies, hit the stims. Your Marines will lose 10 HP each time you stim them, but your Medics will heal them of that damage very quickly.
As you continue to play StarCraft: Remastered, you can develop this strategy to include more advanced Terran units like the Siege Tank and Goliaths to become an even more capable fighter.