Among the first things that you need to consider is the type of space you've got. You should be able to identify the kind of environment you are going to install your overhead fan units. This means properly determining the size of the room and the corresponding air circulation that it needs. Thus, you should pick out smaller fans for smaller rooms and bigger fans or multiple smaller units for large-sized rooms. Understanding your ceiling height is also important for you can't put standard units on either low- or high-ceilinged rooms as there are overhead fans designed for such spaces. For low ceilings, there can be the hugger types. As for rooms with high ceilings, there are downrods which can be attached to help bring down the fans closer to the occupants inside the room.
The next thing that you should carefully consider is the style of the ceiling fans. Your choice of style largely depends on the style of your space, too. What you should do is identify the theme you've got in your room. Do you have a formal space or a casual one? Does your room exude a traditional look or a very contemporary design? Apart from these, an additional consideration should also be exercised especially if the room is intended for use by the little ones. Thus, you can make your selection from classic, casual, traditional, contemporary, to even juvenile styles.
Last thing is to consider the finishes of your units. Surely, you'll be getting ceiling fans from durable brands, and so, when you expect that your overhead fans will be with you for many years to come, it becomes imperative that you get finishes in blade and housing that will really look best into your space. To get a perfect match, you should try complementing the tones of your blades and housings into the color of your furniture or molding. That way you can have a well-orchestrated design that wouldn't clash but would rather look well put together into your home.