A useful tip to bear in mind is that hired soldiers via the barracks (that cost $15 per) have more health than the default rosta of 12 soldiers you start with. Admittedly you have to pay for them and they take 3 days to arrive but you will need to hire some at some point no doubt...
Also, starting via the tutorial isn't the best idea in the long run. You get a free Officer Training School but moreoften than not you'll want to build that yourself later in the game as you get to chose exactly where to build it. The top left of the "ant-farm" I personally find far more useful for satellite uplinks and the right side for OTS, Foundry, Alien Containment etc (and also depends on your Steam vent positions too).