I thought this would be handy. A one stop post which quickly summarises (is that redundant phrase?) what's exciting in an adventure, and what isn't. What should you have, and what should you avoid?
The Good
Exploration - making every crest of a hill a new adventure
Social interaction - Charming, intimidating, cajoling, seducing, bluffing, persuading etc
Mystery - puzzles, dilemmas, working things out with brain power
Tough Decisions - most choices characters make should be difficult ones. Yes you can burn down the barn to destroy the orcs, but what about the dozen villagers trapped in the loft?
The Bad
Too much combat
The Ugly
Railroading - wherein players don't really have any meaningful choices to make, the GM merely prods them from one encounter to another, regardless.