Here's my own Satellite-Lofter. It's a 3-stage design, often achieving orbit with the first two stages alone, depending on payload weight and whether you add legs to later make landing smoother. The craft is designed for powered landings, BTW as leaving a NERVA engine in orbit would get the Green-kerbs panties in quite a twist.
Stage 1 has a 3 meter diameter and uses 7-kerosine engines, and 6 stabilizing liquid fuel thrusters. This one's a beast and takes some skill to fly, since if it tilts over more than a couple of degrees you'll never right it. As you go higher it's recommended to throttle the engine back down to reduce both air drag.
Separating stage 1.
Stage 2 has a 2 meter diameter and uses a single, massive engine. Until about 30 km high, I keep throttling the engine back.
....at 30 km, I increase the angle to about 45 degrees, starting to pick up lateral speed. I also increase engine output as gravity drag decreases, and it makes sense to burn fuel now when the Oberth effect is stronger.
....at around 45 km, we complete the turn to lateral thrusting and give the engine all it's got to take advantage of the Oberth effect.
Separating stage 2 and jettisoning the protective cone over the cargo. Since the cone's decoupler is somewhat anemic it's necessary to do a short side-ways burst.
Stage 3 is a NERVA engine with a massive, 1.75 meter fuel tank.
Orbital speed achieved, releasing payload. Note that I still have loads of fuel left, so I could loft this thing into a lot higher orbit, as is, it's on a highly ecliptic orbit.
Commencing retro-burn to re-enter atmosphere. I waste a lot of fuel, as this could be done a lot more efficiently by burning at periapsis and aero-braking.
Deploying chutes when air-speed has dropped below 300 m/s
Safety burn, slowing the craft below 80 m/s, so the chutes are not ripped off when they fully deploy.
At 500 meters altitude, the chutes automatically expand to their full size
Maintaining 9-10 m/s descent rate until the last 100 meters of altitude, when I increase throttle and land gently at 3-4 m/s.
Safely landed - on WATER! Expect a wet splash in later versions!