Glance through the recipe instructions before you begin. Some recipes ask you to chop veggies in the middle of the process, usually while something else is cooking on the stove. I recommend ignoring those instructions. Instead, prep all your veggies before you do anything else. (You can preheat your oven during this time). If you are anything like me, trying to chop vegetables while watching over the cooking process will usually end up with overcooked or burned food, or even knicked fingers.