Hello, I've been learning about the Adobe suite by trying to create new maps in the style of old rpg's. I've been working in Illustrator and have much of the map done, but I'm trying to figure out how to reproduce the look of the grassy areas, the empty dirt lots with their textures, and maybe even that watercolor look of the concreteClick image for larger version. 

Name:	TSR6850.Basic.Map.jpg 
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ID:	90143 in Illustrator. Maybe it's better to do this in Photoshop but I'm not sure of how. Last time I tried to do it in photoshop and import it into my illustrator map, but the small patch I made took up a crazy amount of memory and choked out the program. Any ideas? The style I'm copying is from the old TSR Marvel Superheroes rpg which I have posted above.