A lot of it comes down to knowing where to find science. You'll discover that with default settings (Normal difficulty), it's actually quite quick and easy to get through the early game. Also, focus on the world-first record contracts. They throw absurd amounts of free money after you for basically doing what you would be doing anyway (accelerating to orbital speeds etc). You can make half a million funds in a few simple launches with only one or two tech nodes unlocked. I usually take my time w