The secret to cooking really good food lies in the quality of your ingredients. I've heard this many times, but I have finally come to believe its absolute truth with my purchase of good quality balsamic vinager ($8 bottle from Buon Italia at the Chelsea Market). It's like I never understood vinaigrette until now. Thank God the movers wouldn't allow me to lug that cheapo balsamic vinager from San Francisco.
Fresh. Always. Fresh ground pepper. Fresh herbs. Fresh seasonings and spices. Have you ever grated fresh nutmeg (it looks like a funny nut) on top of creamy fettucine? It's magical.
Kosher salt for seasoning your water before adding veggies or pasta. Thomas Keller says you should cook veggies in water so briney its salt content resembles that of the ocean. After much experimentation, I concur.
Homemade stock. There is simply no substitute. And homemade veggie stock takes less than an hour to prepare and freezes beautifully. On Sundays I like to make a batch and freeze it in 2 cup quantities.
You'd think I'd have more to share, but that's it, those are my secrets. Quality, seasonal ingredients, as fresh as you can get. That's the difference between so-so food and "Wow! That's the best carmalized onion I've ever tasted!" meals.