I do a lot of work as an author, game designer, art director, layout artist, and publisher.
So I am here to post some more of the tools I use. This time lets look at some of the things I use to help design encounters with.
Template for writing location descriptions stolen from Martin Rayla of Treasure Tables (now of Gnome Stew)
Unusual Places you need ideas from the real world before you throw in magic or fantasy too keep your players from getting too used to simple terrain features.
Your encounter now has a stage, now thin about how your going to light it. What about the weather there? Even underground you can have shafts of rising and cooling air.
If your outdoors you can have some amazing or unusual phenomenon that creates strange light or perhaps the locals like to do fun things with mirrors or magic, spotlights, deep shadows, magically enforced utter darkness, strobe effects, scintillating colors, rain, fog, sleet, hail, lightning, wind, dust devils, tornados, hazards & disasters waiting to happen etc.
The Book of Challenges which Mike Selniker worked on, has an introduction that is worth the price of the whole book. But I will sum it up here for encounters: Box them in, Split them up, Show them one thing and give them another, Make them dig deep, and Hang'em if they can't take a joke.
Use iconic monsters with new twists ! The monster template is perfect for this and its easy to adapt to any game. I like Advanced Bestiary by Mattew Sernett (everyone should own this, if you play any d20 fantasy game), Book of Templates: Deluxe Edition, the whole Template Troves series, I kinda like modifying monsters, If you had not noticed already.
Your players probably have a particular hatred or fear of one kind of monsters. That’s because they have encountered it before and you can milk that emotional reaction. The same goes for iconic Npcs as Brandon Hodge shows us (and Ken Hitte has been telling me for a while)!
New monsters should be used very rarely, fear of the unknown is great, but unless its truly a memorable encounter think about using something else first. Remember GM know these monsters as well and it cuts down on their prep time if they know the monster already. Tweaks and modifications can still surprise players.
Iconic Monsters also have the advantage of rarely being utterly retarded monsters, of course what do I know.
Finally combine everything you have here, remember what I said about show them one thing and give them another, what if your monster was in disguise? A fire giant disguised as frost giant, "Oh no mr. wizard don't use the fireball on me!", then you make him a Jotunblooded Giant, You can now stage the fight in a crooked forest, with high winds at night, then a forest fire starts raging, and fire whirls start to appear!