It is tempting to snack on the items you're working with, I know. Sometimes you're not even really hungry, but you pick because it's there. Whether it be cheese or veggies, it's hard to resist sometimes and even harder if you are hungry after work. And harder still if it is an irresistible ingredient.
Prosciutto is my kryptonite.
The same is true with the post-prep. Like when you have a sauce going--or a batter--or a side dish that is already done and waiting for the meal to be served. Don't sneak a "taste" or you'll have this potentially great end product and no longer want it because you are full. There is nothing worse than not being hungry and having to sit through a meal and wait for others to finish. I have the patience of about zero so you can imagine my inability to go through this.
The long and short of the tip: Don't snack on your meal. Wait to actually sit down to eat. Some helpful ways to deter snacking are chewing gum while you cook, brushing your teeth--that kills the taste of things--or putting in a teeth bleaching tray...this will keep you from eating and beautify your smile. :-D