Here's an actual example of how I utilized the ideas I went over in Monday's post to design an adventure. I'll also go over how it actually went with the players at the table.
This was the second session in a new campaign. In the first session the party was kidnapped by pirates who were planning to sell them as slaves to someone out on a small island. The group killed most of the pirates and ended up safely at the island. They weren't sure why this person needed so many slaves, and at the time neither did I.
The first session gave a good goal for this one: to find out what is happening on the island. Using character backstories, I decided on the answer: a mad scientist making an army of half-beast, half-humanoids for the local ruler. They could encounter these hideous beastmen in the climax of this session and then stop the scientist in the climax of the following session.
I chose the random encounter early: a group of wolves on the hunt. It’s an easy combat that makes sense for a largely uninhabited island. Plus one of the player's miniatures was wearing a wolf skin and he was concerned with how the character would get it in the game. I never needed to use this scene. He'll get that wolfskin sooner or later.
Scene One: Pirates and Planning (Non-Combat)
I had left the group on the boat and didn't feel I could just narrate them onto the island, so the session opens with the party on the boat. I had the surviving pirates point out that the buyers would be expecting to receive the latest shipment of slaves on the shore. The players decided to ambush the islanders by pulling the old wookie-in-fake-handcuffs trick.
Scene Two: Prisoner Pickup (Combat)
A lieutenant and a few guards come down a raft to pick up the "prisoners." I gave them a big cage to transport their new slaves to up the ante and encourage some sort of confrontation.
Their ambush went off without a hitch. A spell or two was spent, but little damage was taken, and they had a chance to interrogate the prisoners, getting hints about what's going on. They decided to go through the forest to find the scientist's compound.
Scene Three: Goblin Trap (Non-Combat)
I wanted to add a third faction into the mix, a group of goblins who also oppose the invading scientist and his followers. They booby-trap a dead guard and leave him on the side of the river. This would provide some nice foreshadowing for the next combat encounter I had planned.
Since the players took the forest instead of the river, this was skipped entirely. I could've fudged my plans and moved it to the forest, but it wasn't a major scene. I always want to reward players for taking less-obvious choices, even if they never knew that they avoided a trap by taking the forest.
Scene Four: Goblin Ambush (Combat)
Here’s where I put in some actual goblins, patrolling the river and the forest for strangers. They may even get a chance to ambush anyone coming down the river. Being a cowardly lot, I thought it likely they might surrender and even invite the players to their home if they figured out that they were working toward similar goals.
Thanks to some good rolls and smart interactions in the goblins' language, the players convinced the goblins that they were on the same side. Combat was entirely avoided. I could have had the goblins attack despite the players’ actions and force a combat encounter, but what would’ve that accomplished aside from demonstrating that the actions of the players didn’t matter.
Scene Five: Goblin Lair (Non-Combat)
I came up with a few things to interact with in the goblin cave: an altar decorated with jewels, a giant spider hiding in the ceiling, and lots of goblin beer that would give the players disadvantage on upcoming rolls due to intoxication. I figured there was a pretty good chance that someone would attempt to steal the jewels and trigger a combat. This scene would lead into the next at any point once it was starting to get boring.
The players really enjoyed interacting with the goblins, so I just kept going along with whatever they wanted to do. They even bother trying to mess with the jewels, and instead deepened their relationships with the goblin tribe.
Scene Six: Beastmen Attack (Combat)
When the group sent to pick up the new bodies don't come back, the others back at the compound send out a stronger force to see what happened. They could pop in on the party essentially wherever they may be.
As I hoped, this was a good battle, with the players utilizing many of the features I had already established in the goblin cave. The aid provided by their new allies countered the handicap of fighting while intoxicated. I’m not usually overly-descriptive when I DM, but this being the climax, I tried to really lay into the monstrous and unnatural appearance of the beastmen. After the fight, the goblins pledged to help the players storm the compound, setting our goal for the next session.
The whole session took about two hours, even with one scene entirely skipped, no random encounter, and one possible combat avoided through diplomacy. I feel that the players were engaged with the story and had a good time, which is always my goal. Most importantly, by setting a clear direction for them, they are excited for the next session so that they can continue the journey.