This one is going to be short & sweet. Promise!
The absolute best advise I can give for eating out...look up the nutritional information before you go (if available). Have a plan in place! Know what you are going to order before you get there and are too hungry to make healthy choices!
I am always SHOCKED by the calorie/fat content when I look up a restaurant's nutritional information. It will definitely make you think twice about what you order....or whether you eat the entire dish or just 1/2 of it. Most chain restaurants have this information readily available to you on their websites.
So just a little tip. I don't always practice this approach, but I know when I do, I eat FAR fewer calories!