I make serious notes and when a color is settled on, I add it to a word document that I keep running on my computer. I keep a pringted copy of the document on my work area for quick reference and if I change anything , even just a hair, I note it on the printed copy. I take that copy to the computer quite often to up-date or add to the word document.
If I am developing a color I generally begin the process with a 4 ounce batch.... just in case. When I settle a color at that size, I try one at a cup using the same ratios X 2. If I want a 6 ounce batch as well I do a shot at that level too. I note any adjustments I have to make and where needed I split the color recipe into 4, 6 or 8 ounce batches to keep things consistent.
I use a popsicle stick to dip out glitter and hi lites. I've drawn a couple lines across the end of each stick so I have a reference point to follow. Glitters are hard to mess up but that hi lite can go from great to "holly moly what did I do wrong here?" real quick. If I am not real sure about how much hi lite to use I adjust as I go just to keep a handle on the results.