Links

GRAPHICS

GRAPHIC TOOLS FOR MAPS

World/area maps:

City Maps

Dungeon/building Maps
DIY
GIMP, essentially free Photoshop. You can take google maps or other images and alter them in GIMP. Very powerful, but the learning curve is steep. https://www.gimp.org/
Inkscape, essentially free Adobe Illustrator. Very powerful, but the learning curve is steep. https://inkscape.org/en/
Galleries of free or cheap premade maps:
Advice from pros:

Graphics: TOKENS

GRAPHICS: CHaracter ART

SPECIFIC MODULE ART