Keeping a log of all the castings you pour is the best way to get repeatable results. I record every pour that I do now, and I refer to my log book daily!
I’ve also created a PDF template that you can download and use for your castings.
It includes all the data that I record for my pours plus an area for notes. The PDF is two pages, and the first page has some example data written as a guide like the picture above. Page 2 has been left empty, so you can just select Page 2 when you print it out. You can print a bunch of pages and staple them together, stick them in a binder, or go all-out and make your own DIY notebook. Bob over at I Like to Make Stuff has a great video that shows you how to do it quick and easy. You’ll just need to adjust the dimensions to fit the log book template.