A creative use of color shades can help you to create accents with your trim without deviating from the original color of the walls. For example, if you want to paint your walls a light brown, then try a darker brown for the trim. The contrast in shades within the same color spectrum would be an interesting way to maintain the room color theme between the walls, furniture and trim.
The colors you choose for your wall trim should fit the size of your home, as well as your color scheme. For example, larger homes tend to offer more window space and greater access to natural light. That means that darker colors would look more appealing in a larger home. Painting the walls an off-white with dark red trim would accent the space inside a bigger room better than brighter colors.
One of the advantages to painting your trim the same color as the walls is that you do not need to worry about the extra preparation work involved in separating colors. But using the same color for the trim as the walls can help a room seem larger. The walls look larger because it is all one color from the ceiling to the floor, which gives an expansive feeling to the room.
You can use your own personal preferences to create the color combinations to be used on your walls and trim. For example, if your favorite sports team's colors are blue and gold, then you can paint the walls blue and the trim gold. The color scheme from a favorite movie poster or colors associated with your favorite musical act could also be inspirations for your wall and trim color schemes.