clean the image/building

 add other elements

 make use of the effects in photoshop such as changing the layer mode to subtract.

Final image below.

building : http://vistalore.com/wp-content/uploads/2015/02/1024_fantasy_art_scenery.jpg

fish : http://www.wallpaperup.com/uploads/wallpapers/2014/11/17/519839/b2272c7b13fcfe0f84fe1bb92d5fdf08.jpg

background : http://www.pixiv.net/member_illust.php?mode=medium&illust_id=48965836

 Find a scenery.

 Fill the sky. Add buildings

 Add plants

 Change the colours

 Refine the background

Add more details and refine the plants and buildings.

Final image below.

background : http://hitfull.com/files/pictures/Zhangjiajie-National-Park-China1.jpg

town house : http://www.tabletop-world.com/Images/TownHouse/townHouse.jpg

town house 2 : http://www.tabletop-world.com/Images/Town-House/TownHouse.jpg

cottage : http://tabletop-world.com/Images/Cottage/Cottage.jpg

town buildings : http://da.reallusion.com/Upload/JIC74b96433ac45a5c33/JIC74b96433ac45a5c33_20120922193005_Header.jpg

tower : http://www.tabletop-world.com/Images/GuardTower/Tower2.jpg

castle : https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Neuschwanstein_Castle_LOC_print.jpg/1024px-Neuschwanstein_Castle_LOC_print.jpg

tree : http://www.speacock.net/albums/album300/2010_Mar_24_SF_Flower_Garden_Show_44_Bonsai_Wisteria.jpg

Final Image 1

Final Image 2