When making new recipes it starts with research. I look into different oils, fats & butters and how they generally react in soap. Will they make a harder bar? Will they create lots of bubbles? Once I have an idea of what ingredients I want to use it all gets calculated in a Soap Calculator to ensure i'm using the correct amount of lye. I'll make the recipe, allow it to cure, test & tweak. Once I'm happy with it I can send it off for it's safey assessment (Cosmetic Product Safety Report).
When I'm making a soap that I already have assessed and I'm making it for stock/an order I start by deciding what size recipe I need to make - one loaf or three? There's more in the prep than there is in the actual making - herbs need infusing, hard oils and butters need melting, lye solution needs making so it can cool down.
I keep notes as I go regarding the ingredients as this is all required for my Product Information File.
If I want to create a new design in the soap then I'll spend some time drawing that out or planning what steps I need to take - do I need to colour only a portion of the batch? Do I need to make half first so it can set before pouring the rest?