1) Give yourself enough time...
New recipe? Don't wait till 15 minutes before you want to serve dinner to try it. Ship off the kids, make yourself a drink, if you're so inclined, RELAX, then start.
2) If using a recipe for the first time, read it all the way through before you start. Now if I had taken this advice everytime I used a recipe, I would have had a lot fewer cooking headaches. And remember, most people that have some experience cooking just use a recipe as a jumping off point.
3) Try to use fresh stuff...peppers, onions, mushrooms, garlic...The difference in taste is amazing and it takes a lot less time than that game of hearts on the net that you have to squeeze in before dinner :) Exception - tomatoes, for a variety of reasons I'm too lazy to list right now. UPDATE - Val is a new convert to FRESH HERBS!!!! Same stuff applies.....
4) If you've never done any cooking before, do yourself a favor and buy a good, all-purpose cookbook. I recommend Better Homes and Gardens New Cookbook. I've been cooking for 20 years and still use it all the time.