While the colors matches the cartoony approach your wanting to achieve out of this consider making feature the theme so it doesn’t look like a bland design. It needs to be more spooky in order to fit the Halloween theme, it is a time where you go with adding the proper details to the land and house itself. Add some abandoned items around the area or different structures, or some spooky looking props to fit with the design so it’ll match the setting.
There are many types of ideas that you could brainstorm. Add some dried trees along the entrance cobwebs certain parts across the surface, always use reference images of the things your trying to create as it’ll help getting those important details.
Otherwise it’s a start consider to improve it more further i would encourage you to add variation into the trees and use reference images if your losing ideas on what to add next.