A friend had a useful trick, especially with Indian restaurants: if the kitchen is accessible, try to walk past it. If your nose tries to drag you back, it's a good sign.

Myself, I follow the somewhat negative method of checking the menu for expressions which don't tell you anything about the product but are just there to sell it. More than two and I'll go elsewhere. Remember, if offered a generous portion of tender oven-baked haricots smothered in a delicious sauce made with sun-ripened tomatoes and exotic spices served on a doorstep of locally-baked bread toasted to perfection, you'll still get beans on toast.