I am so bad at delta-V...
I just unlocked the new science lab module. I'm pretty sure this didn't exist the last time I played KSP. Anyway, I built a new Minmus lander loaded with science, scientists, and this lab, and sent it to the North Pole of Minmus.
Well I get most of the way to the ground and my final stage has completely run out of fuel. No chance of landing, no chance of returning. I decided to at least watch the crash. The lander impacted at about 60 m/s, bounced a few times, and somehow survived with no damage... Given Minmus' low gravity, I was able to use the reaction wheels to rotate it and park it upright, so I "did science" and set the lab to work and figured I'll send a rescue mission later to recover the scientists.
So I finally turned my attention to the Mun. At this point I've only done flybys, no landings, because Minmus is so much easier to deal with, but I have big boy rockets and modules now and need more science. My first attempt failed miserably when my staging somehow got set up totally wrong, and my command pod separated during liftoff when I tried to eject my SRB's. I have no idea how I managed that.
My second attempt failed because my transfer stage and lander stage ran out of fuel while burning into a transfer orbit to the Mun.
The third attempt failed when I successfully landed on the Mun, did a bunch of science, but was unable to reboard my vessel because I missed one ladder space while building the rocket, and Jeb's jetpack doesn't work well enough in Mun gravity to boost him to the command pod like I could on Minmus. Also, when I started the EVA Jeb fell off the command pod and broke all the solar panels on his way to the ground so even if he could re-board, I'd probably run out of electricity on the flight home. And the lander barely has any fuel left, once again I underestimated dV and I doubt it could make it back to Mun orbit.
I am now taking a couple days' break from KSP to let my frustration subside.