Hello,
The "phase angle" you mentioned is an important concept in interplanetary travel, and once you get some experience you can learn to eyeball most transfers from the phase angle itself, but you may have better luck by searching the term "transfer window" or "launch window". Transfer windows are represented by something called a porkchop plot, and show you a window of time where transfers are possible, and also most efficient.
Here is an excellent transfer calculator
For the purposes of calculating your transfer window, just calculate it as if you were departing Kerbin. The windows for departing Kerbin and Mun are essentially the same since they are both located together in the same SOI.
For planning your actual burn to exit the Kerbin SOI, play around with the maneuver tool, but I can tell you that a good rule of thumb is to make your trajectory such that you are exiting the SOI in the retrograde direction of Kerbin's orbit for destinations in the inner Kerbol system, and prograde for destinations in the outer system.
The final tip is to use this handy delta-v map, as it will tell you any additional delta-v required for plane changes, if you ever need to do that.
fleventeen's post in spawn a vehicle on specific planet? was marked as the answer