Got a rover to the Mun today and explored a few biomes. I think I've finally got the hang of doing stuff in Kerbin's sphere of influence, and am about ready to start sending stuff interplanetary! Anyone else been up to anything in the Kerbol solar system?
It's really unintuitive at first, but what really helps is getting a mod that provides more telemetry data on your ship and orbital path. The game doesn't really provide any of that in vanilla, so having it is useful in avoiding basing everything on guesswork or actually having to break out some math. Since playing this game I've learned so much about how space travel works, and can actually understand a lot of what NASA does now.
Kerbal Engineer, it does all the fancy calculations for you in real time so you can get your orbits and landings super precise and efficient.