Are you pressed for time?
A leisurely session is better served by carbon fibers while a ceramic heater can give you good results quickly. If you are trying to fit a sauna into an already-overwhelming schedule, the ceramic may be your better choice, but if you have a longer time to relax, you might want to consider the carbon.
Are you realistic about how many people will enjoy it at once?
Don't be misled into getting a bigger or smaller sauna than you need. You might daydream about having lots of family and friends over or about the relaxation of a solo sauna session, but your lifestyle and obligations aren't likely to significantly change just because you have a sauna. Be sure to choose the size that best suits the most likely scenarios in which you will be using the sauna.
How will the sauna fit into existing decor?
One consideration when you are choosing wood type is where the sauna will go and how it will fit in. Western red cedar is a deeper, richer color while western hemlock has a lighter tint.