Restaurants liberate you from the task of preparing your own food, but it is better to have
a peanut butter and jelly sandwich at home than bad food at a restaurant. Nothing makes you
sicker than paying good money for bad food.
These are the most important criteria:
If the restaurant does not look clean, the kitchen is probably worse. Skip it. If you cannot smell the food cooking, they are going to serve you leftovers or something that is not fresh. Skip it. If there are no people sitting at the tables, the food is probably bad, the service is terrible, the restaurant is expensive, or there is some reason why the local residents avoid it. You should too.
Other factors in choosing a restaurant:
Sometimes, you can find a good restaurant if you just follow your nose. When I was attending a conference in Santa Cruz, California, some members of our group were walking by a downtown street when we got a whiff of a delicious aroma. It was close to supper time, and we decided to follow the scent to see where it would lead us. After a couple of blocks, we ended up in an alley where an exhaust fan was the source of the smell. We went around the corner to the front of the building, and found a bar that was having a "happy hour" featuring Mexican tacos with chopped grilled meat piled on freshly made corn tortillas complemented by a zesty salsa. It was a delicious and memorable serendipitous experience.