Every story features at least one character, and this character will be the key to relating your audience back to the story. This component is the bridge between you, the storyteller, and the audience. If your audience can put themselves in your character’s shoes, they’ll be more likely to follow through with your story.
Character Creation 101: Better Characters are a Click Away! Roleplaying Tips and Suggestions Creating a Successful Villain Non Playable Characters (NPC's): What's they're really about and more Mapmaking (cartography)
Nice mountains in Photoshop (should work in GIMP too, I haven't tested it yet) One page from there in particular, with useful mapping resources The famous Climate Cookbook First tutorial on applying the CC to a world Second tutorial on applying the CC Some other climate-related tips that I had bookmarked for some reason NASA's very own g-projector, for converting between map projections Software to develop climates based on terrain - there is a free version Designing continents from scratch A diagram for determining climates the easy way Possibly the single best page on the internet for designing a whole planet A collection of map tutorials, as well as some biome guides A satellite map tutorial for Photoshop A guide to rivers Worldbuilding
A load of questions to consider to help you develop your nation Various useful things from the Worldbuilding School r/worldbuilding's resources list Tutorial on good country design Same site, dealing with cities And currency... Guide to a Wiki-Style Factbook, Embassies, and Consulates Generators and tools
Random generators, though more tailored to a medieval/fantasy setting Parliament diagram maker Conlangs
Grammars of not one, not two, but 1,362 languages Flagmaking (vexillology)
Flag designer, browser-based or downloadable for free with more features Guide to good flag design A collection of logo design tutorials Source: Worldbuilding resources for fun and profit (by Vrnallia)