reducing the spike

Another day, another question! Is there a way to tell if a spike after a meal is caused by the bolus timing or an incorrect insulin:carb ratio? Presumably the answer is just to experiment but I'm wondering if there's a pattern I could look out for with my blood sugars/on my Libre graph that...

I read of people on here with amazing HbA1c values. I wondered what would be your three top tips for achieveping these values. I know everyone is different but I would be interested. I keep going back to Pumping Insulin and Think like a pancreas, and they remind me of good strategies. Now I...