Put this Insulin Calculator (scroll to the bottom) at the top of the list of things I wished I’d been made aware of when I first got diagnosed.
It probably took me about 6 months to figure out the exact same conversation rate (base sugar number, plus amount of carbs you want to eat = take X amount of insulin).
It’s a neat little pop-up window calculator, but Jenn rigged a spreadsheet for me that does the same thing. Just wish I would have had this a little sooner…