Greenlandys

Exactly what other people have said, You need to change your ships orbit in order to catch your target. If you're behind the target, lower your periapsis by 10km or so, time warp, and watch as you magically start closing the gap between you and the target when your orbit do pass close again. When you get close enough, then you just have to start using the target on the navball and retrograde / prograde points. But yes, you have to just forget about having a perfect orbit while rendezvousing, Your orbit might go all over the place (If it says you're going to hit Kerbin, you've gone wrong somewhere) but when you get close enough, the orbits and speeds will be so similar that they'll have almost matched eachother.

Look beyond the Mun, at Eve, Duna, Jool etc. Each one is a different challenge to reach and land on along with their moons. Spacestations too! Probably the most infuriating thing to do is docking parts of your spacestation together! Failing that, you can always build some wacky contraptions on the surface. (I know I do from time to time). As for Mods, I only really have Mechjeb and Alarm Clock. Mechjeb for those massive launches that murder my PC until orbit and a bit of other ship information. alarm Clock is really useful if you want to leave a ship on a trajectory and go away to do something else, just set the timer and bam, when it hits 0, you're immediately notified. Really good if you're dealing with multiple ships on the same trajectory.