Basically, you're describing the main problem with the rocket equation: your ability to get to places is determined by the percentage of your rocket, by mass, that MUST be fuel. Most rockets are by necessity more than 80% fuel, and less than 20% rocket. There are some ways to help keep this slightly reasonable, though, especially in KSP, because of the inaccuracy of its physics modeling. Due to how drag is calculated in KSP, the most efficient design is asparagus staging, which is where you have every rocket engine start at the same time, and have a double spiral of fuel tanks, attaching two tanks to the center, and two more tanks attached to those, and so on, with fuel pipes transfering fuel from the outermost two tanks in to the next two in, and so on. After the outer tanks empty, jettison them, and then wait for the next two to empty. Also, if your rocket has trouble lifting off due to the amount of tanks, use solid rocket boosters to help it gain the first few kilometers of height. Mainsail engines provide a lot of thrust relative to wait, allowing them to lift a lot of fuel up, but are not very efficient, so have smaller engines in the center stages, because you only need massive amounts of thrust when you are in low atmosphere, and the big engines will have drained most of your fuel by the time you get into Kerbin orbit. Although more fuel is required by the math, the main skill in the game is figuring out ways to use that fuel more efficiently. Another thing that helps is burning for the Mun at your periapsis, because burning effects the opposite side of your orbit, which would in this case already be closer to where you want to go. If you arrive at the Mun with enough fuel, but run out because of the difficulties of doing a soft landing, keep in mind that until about 5km, your main concern is not how fast you are falling, but how fast you are going sideways. First eliminate most of your horizontal movement, and only then worry about how fast the ground is coming. Good landing legs can take about 3-6 m/s of landing speed, but going back up can quickly add up in fuel usage, so keep a close eye on the vertical speed gauge near the altitude meter, and avoid hovering. Most importantly, don't give up. Experiment with what designs works best, and you should eventually get it! Rockets take practice.