As you have read (in the previous post), essential oils do not go bad, but are prone to a process called oxidation that effects essential oils that are years old. Oxidation takes 3-20 years to affect essential oils depending on the source of the oil. We can limit the effects of oxidation by storing our oils properly. Essential oils should always be stored with the cover on tight because exposure to oxygen speeds up the oxidation process. There are two other things that speed up oxidation: sunlight and heat. When possible, essential oils should be stored in a cool, dark place. Although essential oils do not need to be kept cold, cold will never hurt essential oils, but heat will.
A good recommendation is to keep essential oils that are used everyday in the place where they will be used. Those essential oils that are used daily will be used long before oxidation is a risk. For oils that are used only occasionally, storage in the fridge makes sense. Though the fridge is colder than essential oils need, cold will not hurt oils. The fridge is also dark, so it makes a good storage location. Always make sure that the cover is on tight and store upright.
There are a variety of types of storage containers that work well for storing essential oils upright. There are wooden boxes like this one that are functional and attractive. There are also soft sided containers like this one. The choice between wood and soft sided is really just a personal preference regarding looks, weight, etc. There are also some great display shelves, but remember to consider exposure to sunlight. Lastly, it’s been my experience that 5ml bottles of essential oils typically fit in anything designed to hold nail polish, so a container like this may work in a bathroom or near a diffuser. (But not if they are within reach of small children. Be diligent about storing essential oils out of reach of children and read more about essential oils and children here).