I seriously Th*rked up my last Mun landing attempt. I thought I'd try it Appollo-style, with a lander and an orbiter module. I crashed the lander but kept the Kerbal alive. Realising I couldn't rescue him with the current orbiter, I sent the kerbal in orbit home.
The ship I sent to rescue him was also Apollo-styled, except the lander would be unmanned. I only realised once I got to Munar orbit that I'd forgot to stick solar cells on the ship and the batteries were dead.
So I had to send a third unmanned ship up, which consisted of a couple of RCS tanks, some solar panels and a docking port. I had to dock the third ship to the second lander, rescue the kerbal on the surface, transfer him to the waiting orbiter, then undock the power ship from the lander and attach it to the orbiter.
Overly-complicated mission but all kerbals got home safely.