You have your mood. You have, generally, a climate you want. If you read the linked site, you might even have some idea of how to get that climate.
Now, let's get into history.
No, not dates and names-- that's too recent. We're talking planetary history. How long has your world been around? How old was it when your sapient species reached it (either through evolution or discovery)? Did a previous species dominate, like the dinosaurs, leaving a fossil record? Or is human(oid) evolution the first major species to leave a lasting record? If a previous species was sapient, did they also leave artifacts of their society?
A fossil record can be misinterpreted in many creative ways. You might end up with legends of dragons based on dinosaur records-- unless, of course, you have *real* dragons on your world. Your current sapient beings might believe in an older race that "built" everything, when in fact that older race actually destroyed it.
Also look for the non-biological records of physical change. Most geography changes slowly. You'll find that mountain ranges take forever to grow, except when they don't. When they change suddenly and dramatically, people remember, and their attitudes about such places change as well. Worldwide legends about sudden changes may spring up-- nearly every Earth culture has a flood story. There may be a historical record there, or there may be a parable being told instead. But they all have one, and there's therefore some kind of scar on what humans perceive of as their planet's history.
For example, consider earthquakes and volcanoes. Any seismically active region will gain a reputation, perhaps as a place where geographical records may be upturned rapidly (in the case of a tectonic shift bringing a fossil to surface), may be destroyed or buried quickly (perhaps by volcanic mudslides), or may be altered rapidly (such as by a more dramatic volcanic eruption that not only buries but also relocates debris for several miles, or an earthquake that opens a rift in the center of town). In a scientifically advanced society, your seismic causes won't hold all that many surprises for your characters, unless you want to set forward a speculative question about geological cataclysm (such as a non-earthly cause or something unearthed that's unexpected). For your fantasy characters, of course, a volcanic eruption can be an enormous deal-- the wrath of the gods, a dragon awakening, or even a magically-induced catastrophe.
Other major, fast-moving cataclysms include hurricanes and flooding, fires (though recovery from fire is actually a fairly rapid process, taking a matter of years), earthquakes, volcanoes and rifts, and meteroites. Less rapid but still quick in the geological scale are glaciers, ice ages, and global warming. A good example of a very slow-moving but planet-changing event is the plate tectonic shift that essentially moved India into Asia, forming the Himalayas and causing a massive climate shift in Africa, drying the continent out and forever altering (or perhaps just starting) the course of human evolution.
Even though we're not yet into culture-building, start thinking now about what kinds of scars your planet might have from major cataclysmic events. What major mountain ranges do you want or need to put into your story, what deep canyons, what crater-marked plains? Are all of your scars natural, or are some man-made through technological or magical forces?
For 15 minutes, jot down some of the Really Big Land Features you want in your story and just think "what if that were made by...." Write down a couple of causes for those features and scars, and stick it all into your notebook. Which scars are slow-force scars (like plate tectonics), and which are fast-forces (anything that takes less than 10,000 years is medium-to-fast in geological scales).