Colors
Focus on colors. The scenes you're looking at are going to be busy and have odd objects scattered through them including animals on bookshelves or small items, like pins or needles stuck in a piece of furniture. Hidden object games blend the objects into the scene. Think of the typical colors of the object for which you're searching, such as a red fire hydrant or black and white stripes for a zebra. Breaking the scene up into colors turns it from a big mess into individual sections.
Shapes
Part of blending objects into the scene, as opposed to making them obvious, is to place them in similar shapes. Long, narrow objects commonly exist in door frames or on the wall in the same pattern as the pain. They also may go across the ceiling. Don't over scrutinize and assume that every oddity is something you're looking for. Game developers throw random objects that have no relevance to the scene or your objective to throw you off-base.
Switch Scenes
Many hidden object games do not thrust you from one solid scene to another. They allow you to switch between three or four scenes to find objects, many times because you need to use a hidden object on an item in an alternate scene. If you've been staring at the same scene for awhile, switch to another one and come back later with a fresh set of eyes.
Timer
Hidden object games utilize timers to encourage you not to sit and spend hours looking for a single object. Don't click randomly on the scene hoping to find an object on your list because excessive clicking has consequences, typically taking precious time off the clock or obstructing your view temporarily to halt progress. Analyze the object carefully to ensure it is what you're really looking for.