My family loves to go out to eat, so I've had to develop several strategies that I employ (depending on the restaurant and who I'm with):
Offer to share a meal
Order an appetizer (this can be troublesome because they can often be fried or covered in cheese)
Order a kids meal (most restaurants will allow this, BUT it's also a risk because a lot of restaurants have unhealthy kids meals like chicken nuggets, french fries, mac&cheese)
Order a side dish (You can usually find relatively healthy side dishes, they won't be high-protein, but it may be the best alternative depending on type of restaurant)
Ask for or bring your own "to go" containers.
Lastly, and this was my newest revelation: some restaurants allow people to "add on" protein/meat to an existing meal. EX: my husband ordered a regular meal and we "added on" 4 grilled shrimp. This was PERFECT for me. I had the shrimp and ordered a side of broccoli. Best meal EVER!