From your standard construction pattern, it seems as if you have a problem with too-long rockets. This is one of the mistakes I am also prone to do. Basically, imagine the following: Take a long ruler and push it from below. If you begin slightly swinging it, this vibration will continue.
Now, take an eraser and stick it on the top. Now, every time you move the ruler the vibration gets even stronger. This, of course, makes the rocket much, much more unstable. That was the problem of Minmusshot IV.
Now, from my experience, you can do a Minmus return with just a tiny bit of fuel. The Minmus to Kerbin stage you had shown last is probably nearly enough to get from Minmus orbit to the surface and back to Kerbin. Probably.
Then, a tip for general rocket construction: You want it to look roughly pyramid-shaped. So, try this:
Take the Kerbin-Lander and the Minmus --> Kerbin stage as you have designed. Add a single Science Junior plus two of the Goo canisters to the Kerbin lander. One single science mission with them should bring you about 100 science if you return them.
Then, add a single Tricoupler under it, and add three fuel tanks plus engines there. That's all you'll need. Build your stages from those three, with three decouplers and struts between them. That should probably work and - if you don't make the rocket too big - be maneuverable, too.
Lastly, there is a tip I can give you: Use either MechJeb or FlightEngineer (haven't used the latter). Not for landing, just during vessel building. This will give you information about the thrust to weight ratio (which could have prevented something from your past...) and the available deltaV. With the KSP Cheat Sheet, that should help you calculate the actual requirements. Of course, you could do it per hand, with enough time, but this generally makes it easier.
"Shoot for Minmus, for if you fail, you will explode among the stars."
--Unknown (possibly because he exploded)
Shoot for the moon.