This is advice I've given before, but I think it still holds true.
In my opinion, the most important resources you can have when writing for publication or writing for homebrew are:
- an inquisitive mind that asks "How can I use this?"
- a notepad
If you're at a zoo and learn about the ecology of desert, make a note.
If you're watching Mythbusters
and Jaime and Adam fail to blow something up because of some scientific reason, make a note.
If you're at a museum and wandering through the ancient jewelry section, read the little placards. Then make a note.
If you're reading about some territorial dispute in a far corner of the world and there's a hyperlink on the history of the conflict, click it. Then make a note.
The importance of actual experience cannot be understated.
If you've never been in a real cave and you have the ability, go. Then make a note.
If you're never been in an actual forest and you have the ability, go. Then make a note.
If you've never been in a walled city or castle and you have the ability, go. Then make a note.
If you've never ridden a horse and have the ability, do. Then make a note.
If you can't do any of those things, or if you have questions about anything, the Internet is your friend.
I'm partial to several sites, like:
"Just what does the inside of a volcano actually look like?"http://www.goodearthgraphics.com/virtua ... rtube.html
"What is the word for 'chief' in Swahili?"http://www.freedict.com/
"What the Hell is a tourmaline, anyway?"http://blueceylon.com/gemstones.asphttp://webmineral.com/
"What job does City Guard Gustav's father have?"http://www.castles-of-britain.com/castle32.htm
"How can I play the sound of a zombie groaning in-game?"http://www.mysoundfx.com/home/sound-effects.html
I bookmark any interesting sites I come across, and throw them into a big ol' folder (sorted into Language, Historical, and Utilities) that I call RPG Resources.
Anyway, I hope all this helps.