I’ve been a gamer since 1979, starting off with a D&D box set and chits instead of dice. (you young folks don’t know how good you got it with your fancy dice!) I’ve used hex paper and colored pencil to create many a world for D&D and Traveller (and others)
Maps have come along way, but I still have a place in my heart for the old fashioned hex based mapping and adventuring in the wilderness. Hexographer by Inkwell Ideas is a great tool to create even whole world maps for your games. They are currently in the middle of a KickStarter for the Worldographer update to the software. It’s worth a look and I feel it’s a good investment in the next version. They will have the ability to drill down from a planet size map to the specifics of the area, as well as add notes to the various features. They’ve been supporting the software for a good long time and have a solid rep.
Check em out.