Good tutorial here
artofgregmartin.com v. xiv
| Please take a moment to tell us what software you use | A guide to the depiction and creation of Fantasy Cities | Create a non-destructive editable map in photoshop | Believable mountain and forest boundaries | Positioning Names on Maps | My Portfolio
Cool. For pictures of stars you might use to draw them: HubbleSite - Picture Album: Stars
The best maps are the ones we like the most after looking at the longest.