The game is rigged abd unwinable, so don't get disheartened when you fail.
More often or not, you'll hit level 4 without trying on your first go.
Just make sure you always have 50 of your team in research.
As the puzzle is random in every round, you'll have to add staff to other continents in the best order for your game.
Just make sure the blue line doesn't rise too much.
Really, the game talks you through the first one anyway, theoreticall should hit level 4 in round one of three. I know a few people who got it on their second round.