A Chef Card can be a very helpful tool in communicating with restaurant staff about your food allergies. Depending on how you customize your personal card, it can list the foods you are allergic to, alternative names for your allergens, and/or how to safely prepare your food to avoid cross-contamination. Of course you should always ask to speak directly to the manager or chef to ensure their full understanding.
Here is a list of websites where you can either make your own Chef Card to print out or order premade cards. One site listed below even has translation cards available to use when traveling.
http://www.selectwisely.com/ (Translation cards)