Let's suppose we want the players in a campaign to run across an island.
First, we have to get them there. The standard way is to have an NPC say, "Go to this island." We might appeal to the players' desires, saying, "There's a lot of treasure on this island." But these things are heavy-handed. We'd prefer something subtle.
Well, it's an island, so presumably the characters are aboard ship. I've had players who simply refuse to board ships because of storms and the fear of being lost at sea, but we'll suppose that the players have a reason to travel. Perhaps they desire a change in scenery. Perhaps the weather is bad and they seek warmer climes. Perhaps they've been made agents for a company - that should be fairly easy to arrange: "Please go to this other continent and tell the town fathers we can supply them with such and such an amount of wool for such and such a profit, and, oh, take this letter."
We want the party to land on the island, so we'll need a good reason. There's a storm and a barrel of water has gotten loose and broken. The captain is seeking fresh water. He is looking for an island where there might be some. Perhaps some of the meat aboard has gone bad and to keep up morale, the captain wishes to hunt for some large game on the island. Perhaps the captain has some messages for a small colony on the island. Whatever the case, we don't need to force the party to go ashore - we just need to make the island inviting.
What kind of island is it? This depends on the latitude. A rocky island, such as those in Greece? An island of tundra, with few trees? A tropical island, surrounded by a reef or perhaps with mangrove swamps? Possibly a temperate island, like an island off France or a shoal such as Bermuda? We could have a heavily forested, rocky island such as those off the coast of Alaska or Canada. Whatever we choose, it should suit the purpose the captain has for stopping there.
Vila Franco do Campo, literally half a kilometer from another island in the Azores, Sao Miguel - but of course we can put it anywhere in our world we want. Follow the link to give you a series of excellent, detailed shots of how the island looks from various angles. It's easy to get a rich feel for the place.
Imagine the characters aboard a ship approaching from whatever side you like. How would you describe the island? Note the difference in hue between a sunny day and an overcast day. Note the white water on the left side of the island vs. the comparatively quiet water on the right. Is the island inhabited, as shown, with roads and possibly a less anachronistic house? Or do we want the island to be deserted? That depends, again, on the captain's reason for stopping.
Let's say that it's quite close to its present appearance, except that the pathways are not paved and the hill not terraced. The volcanic bowl is too shallow for the ship, but the captain orders a long-boat to be steered into the interior and beached. Men with baskets, bows and axes climb onto the land, seeking wood for carpentry, water, game and provisions. Does the party want to go?
Probably yes. They might feel uneasy about it or indifferent. We may have to entice them. Saying there's a visible cave is often enough, but let's seek for something less pandering. The cleric is asked along to lend some moral support or possibly aid if someone is injured. The fighter is asked along in order to help with the windlass over the island's well, which is temperamental and takes energy to turn. The mage 'remembers' that there's a songbird on the island that's an ingredient in some potion. Never underestimate the power of non-player characters willing to ask for help. Never doubt the player's willingness to seize some small advantage that arises from being in the right place at the right time.
We'll presume that the party is ready to go and is climbing into the boat with the ship's crew. As we push away from the side of the vessel, we'll want to take that moment to add description. We want to make the party feel as if they're taking a bit of a journey from the ship to the beach. "The island looms . . ." - or it swells in size, whatever cliche works for you - these words become cliche because they work. The island looms . . . it makes sounds . . . the party can smell dead fish on the beach, the sweet odor of tropical flowers . . . whatever we can reach for to make the moment mean something. The lapping of the water on the side of the boat, the grunt of the men at the oars, the quiet call of the mate, whose nature is that he does not yell at the crew. "That's it men, pull, pull, steady on, they'll be fresh meat tonight, pull, pull . . ." All this helps put the player's mind in the place.
But we need tension too . . . so there's the height of the cliffs, the dense blackness at the heart of the trees, the crew saying to watch out for jellyfish in the water, watch out for falling rock, watch for stonefish, watch that you don't tear your boots on the sharp rocks, watch that you don't eat the fruit if it's too yellow and so on.
Describe the skid of the boat on the rocky beach and the clear, crystal water, so clear it has no color at all. Describe the sweaty backs of the oarsmen as they ship the oars. The screaming cry of something in the wood, that everyone says is a bird - they're sure it's a bird.
What's here? What's to be found? Well, we'll come back around to that.