Before you even make a batch of cp soap, write down your ingredients. This includes the oils you use, the amount of water and lye used, and any additives such as exfoliants, herbs, etc., and the fragrance you use.
Only used distilled water in your formula. This can be argued til the cows come home, but I've tried using regular tap water with several batches, and my soap always came out jacked up! I don't know if I have hard water or soft water, I just know that tap does not work for me. I've tried filtered drinking water and have had moderate success, but distilled is the way to go. Buy several gallons at once. It's something you never want to run out of.
Only use 100% lye in your formula. If it doesn't say 100%, then it's most likely cut with some other chemicals that I would not dare use in my soap. Remember, lye is corrosive. It can burn, and it can kill. Never have lye setting around especially where there are children and pets involved. When handling lye, make sure that you're in an open or well-ventilated space and that you're wearing long sleeves and long, rubber gloves. I've burned myself plenty of times with splashes while stirring my lye solution. Lye can be purchased online, but in 99% of the time, you will be required to sign and fax a waiver form before they will even ship it to you. I've been fortunate enough to find my lye at a small, local hardware store. I buy about 5-6 bottles at a time at about $5.00 each for a 16 oz bottle.
Please, please, please! You must use a lye calculator! You can't just throw a bunch of oils in a pot, and dump water and lye in it and think you have soap. IT DOESN'T WORK THAT WAY!!! The amount of lye you use is based specifically on the type of oils you use. I learned this the hard way. You can't substitute one oil for another and think that the amount of lye you use will be the same. WRONG! Your soap will either come out lye heavy or lye deficient making the soap totally unusable. There are many lye calculators online that are available, but one that I really like is by Summer Bee Meadow. One caveat for those who use the metric system: It only calculates in oz, so you'd have to convert to grams.
Keep in mind that the combination of oils you use will determine how hard or soft your finish bars will be. The general philosophy is that a good bar of soap should possess the properties of being hard, lathering, and conditioning. It's a good rule of thumb, but it's not the only solution. If you do use mostly "soft" oils in your recipe, your bars will take longer to cure.
I like to add my FO or EO at light trace because I never know how the fragrance will react once I add it to my raw soap. It could have no reaction or it could seize and cause the soap to almost completely harden. Once I add my fragrance, I stir it by hand and not using a stick blender as it could facilitate trace.
Lastly, document your findings once your batch is complete. Was it successful or a complete failure? Did your fragrance oil seize in your soap? How does your soap smell? How did your coloring or additives fare? You get the picture...
In conclusion, this is just one of many ways to make soap. I've been successful using these tips. I welcome every one's input and tips. Happy soap making!