I chose all of my lenses because of their abilties to hit a low f-stop (1.4, 1.4, and 2.8) and when in a restaurant, I pretty much always put it at the lowest f-stop available so that I can take in more light without shake or using flash. I would have never been able to get such a crisp image of this cocktail without a low f-stop.
Choose your seat wisely
When you can, sit by a window so that you get all the natural light you can. When it's dark out or a window option isn't available, choose a seat with a hanging pendant or some sort of light over it. If all else fails and you can't choose you seat and you end up in the middle of a restaurant, you'll have to bump up your ISO
I start at 240 ISO with an f-stop of 1.4 and see what my shutter speed is. If it is less than 20, I change my ISO until I can get it to at least a shutter speed of 20 or higher. Below this I start to get a lot of blur since I am hand holding my camera.
I shoot about 5-10 images and about 1 turns out good. This just helps to get one good one if you are shaking a bit much. I shoot in burst mode all the time because with digital, I can delete what I don't need.
Try and spin the plate to where the food is in depth and the background is blurred. In certain situations, you may need to shoot the food from where your companion is eating. Many times, I shoot the dish in front of Jason instead of in front of myself, then switch them. Or I hold the camera above my head for a straight on shot. Also think about using the rest of the table decor or background. Don't forget the details - remember, sometimes the restaurant is as fun as the food!
Half eaten pictures of your meal are never as pretty! Have your camera on the table before the meal, shoot right when it gets put down, and then store it for the rest of the meal and enjoy it.
Don't be afraid to take the photos. Remember - most likely, you won't see any of these people again. They won't remember you and your photo taking for more than a few seconds - so it's not worth being nervous about. That's the best advice I can give you - even if you feel awkward, if you want to do it, do it! It will eventually stop feeling awkward. This goes for anything really. It's become second nature for my husband to wait for food until I take a camera out I have been doing this for so many years now.