Stick with what you know - if you order a salad loaded with cheese and meat, it's going to be high in calories. But, if you stick to veggies, and maybe some turkey or chicken, you've made a smart choice. Talk to the waiter about what's on each dish if the descriptions on the menu aren't clear, and ask to have it made without the high calorie stuff if necessary. And of course, ask for the dressing on the side so you can control how much goes on the salad.
Another possibility for you - a lot of Italian restaurants will have some nice fish selections, consider ordering one of those with some steamed veggies. That makes for a nice, healthy meal. (But check how the fish is prepared - sauteed in butter tends to ruin the low cal approach

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You may have to work at it a bit, but most restaurants these days will work with you if you're trying to identify a lower calorie option - believe me, it's not the first time they've heard it.
Good luck, and let us know how it goes!