Because refrigeration is a good way to preserve a lot of things, that heat, light and oxygen can be detrimental. I find that milk keeps better in the back of my frig than in the front.
Some lessons I have learned (not in any order):
1) Soap will shatter if you put 3 heaping tablespoons of dry TD in 50 oz of soap batter. Don't do that.
2) Read the production description at least three times and check reviews. Didn't learn my lesson the first time and ended up buying more Mica that was not meant for soap. Tossed the first container 'cuz I couldn't use it for anything, the other two containers I can at least use with bath salts. Thought I had ruined 50 oz of soap only to later find out that the colorant I used morphed from yellow to orange back to yellow.
This is even more important when it comes to Essential and Fragrance Oils. Regardless of 'rave reviews', only purchase the smallest available and then test. I still have the majority of a 16oz bottle of FO that accelerates massively. I also have a 16oz bottle of FO that discolored to deep dark brown and that I have only been able to use thanks to
@Todd Ziegler and his ZVS/ZVCS. And when it comes to Essential Oils, you want to follow safe usage rates (see #6).
3) Test batches. Get thee a 4" Silicone Square Mold (a lot of soap suppliers carry them) and test everything; new recipe, new oil, new butter, new additive, new Sodium Hydroxide/Lye Concentration, new TD, new colorant, new scent, etc. It's a lot easier and cheaper to waste a 20 oz batch than a 50 oz batch (see # 2 and #3 above).
4) Notes. Notes are your best friend, especially when it comes to your Test Batches. If you are a professional soap maker, good manufacturing practices demand that you should be keeping batch records, but it's good idea for private soap making as well. That way you don't keep forgetting that Honeysuckles accelerates...until the next time you go to make it and your plan of a beautiful light yellow with a delicate and wispy orange swirl turns into a frantic PLOP and GLOP.
5) When your daughter offers to package all your lotion bars, don't assume that she knows to keep each fragrance separate until they are labeled or to label them as she goes along. We'll just leave it at that.
6) Take your time and breathe. Whether you are making a 20 oz batch or a 20 lb batch or multiple molds of the same soap...make one batch of soap at a time. Too much multi-tasking can lead you to having to toss your soap batter, bowl and all, in a garbage bag, out the front door onto the driveway because you're afraid it's going to catch on fire. This doesn't mean that you can't Master Batch or pre-prepare multiple batches...just don't try to do different batches all at the same time. Remember, you are making a product that will go on someone's body, even if it's only a wash on/rinse off product that is only on the skin for five or ten minutes, you can hurt someone.
7) Have fun. Whether you are making soap professionally or as a hobby, it should be enjoyable, not a chore. If it's a chore, you tend to make mistakes (see #6). And if soap making is an enjoyable hobby, think not just once or twice or even thrice about turning it into a business. I used to love to sew; after my youngest daughter was born I decided to turn it into a business so I could be a SAHM Mom. It's been almost 30 years now since I have touched a sewing machine, that I have done anything more than sew a loose/missing button or repaired a hem. It was partly my fault (see #8).
8) And never make soap that you wouldn't use; failure is always an option and no way would I want to have 50 bars of soap that I can't stand. At the same time, don't cut off your nose to spite your face. I am allergic to Lavender, but I know that it's a popular scent. I dealt with some headaches until I found a Lavender that I can use (with the windows open and a fan blowing) without issue.
Make the soap you want to make. If you want to use Palm Oil...use it. If you don't want to use it...don't. If you want to make Goat Milk Soap or Lard Soap...make it. If you only want to make Vegan Soap...make it. If you only want to use Essential Oils and natural colorants...do it. If you want to use Micas and Fragrance Oils...do that too. Running a business is tough enough as it is...there are going to be days when you feel like crap or are tired or want to go play in the sun or snow, but you need to soap or lotion or scrubs 'cuz you're running low. But to make something you dislike just to make money...no. That's what happened with my sewing business; I started out with what I loved doing...baby and children and when I quit, I was doing bridal and fat women.
I make no apologies for using Palm Oil. If it bothers you, then don't buy my soap. If you don't like that I use Goat Milk, then don't buy my Goat Milk Soap. If Lard Soap grosses you out, then don't buy my Lard Soap. If you don't like that I use Sodium Hydroxide...well good luck with that. The simple fact is...there are hundreds and hundreds of soap makers and over 300 million people in the US alone...I don't care. Just because YOU don't like this or that or the other thing, there are 299,999,999 who do. That's not to say that I am stupid...I do some custom orders, but with restrictions.