You need a tripod as even the smallest of movements can cause a lot of shake in your shot. If you're shooting in a dark restaurant where longer exposures are needed you'll definitely need some way of supporting your camera. Consider using a remote release or your camera's self-timer too as you pressing the shutter button can cause the camera to move a little.
A focal length around the 50mm mark is good for food photography so have a look at a lens such as Tamron's SP AF 17-50mm F/2,8 XR Di II VC LD Aspherical [IF] lens
or their SP AF60mm F/2.0 Di II LD [IF] Macro 1:1
If you're at a restaurant, generally, you'll find food is well presented so you don't have to worry about playing the role of a food technician, however at home, it's a different story. You need check your produce before you photograph it, making sure fruit isn't bruised or bad and that colours are vibrant and bright. If meat's on the menu, don't burn it and keep some greens or seasoning near by as they can help make your image look more appetising. Check there's no gravy escaping over the edge of your plate or crumbs sitting on the cloth before you shoot and take some time to think about your crockery too. For a modern look that's clean and simple go for white plates but if you're taking photos for a particular occasion such as a birthday or Christmas, something more colourful maybe more appropriate.
Shoot a little higher up
This doesn't mean you need to get the step ladder out, it just means altering your angle from how you usually sit when eating dinner at a table, to give the person viewing your photo a chance to see a meal a little differently than what they're used to. Shooting from a higher angle's also useful when you're trying to capture a long table that's set for dinner.
Simple, uncluttered backgrounds work well and if you can't find a place in your home that'll work or you're out eating dinner in a busy restaurant, try creating your own backdrop for the shot. At home a piece of card or cloth will work fine and while you're out, try using the back of a menu (if it's plain) or use a jacket/cloth over a chair. If your substitute background is coloured, make sure there's no colour cast on your food/plate and have a good look around the frame to make sure nothing in the background is creeping over the top or round the sides of your backdrop. Of course you can always use a shallow depth of field (as we'll explain next) to throw the background in to a colourful blur which can add just enough interest to the shot without overpowering your subject.
Get Creative With Depth Of Field
Not all of your subject has to be in focus as slowly blurring part of it can add interest to the shot as well as draw the eye to one particular part of the frame. It works well with lines of produce or where you have lots of the same produce in your shot. You still need enough of the produce to be in focus so it looks like you did it purposely rather than your viewer thinking you just took a bad shot so experiment with different apertures until you find something that works.
Repetition and patterns always work well and for some reason, working with odd items gives you a shot that's more pleasing to the eye. So, when you're looking at which strawberries to use, take three out of the punnet instead of two. This doesn't mean you can't work with even numbers as they can work but the rule of odds is something you should just keep in mind.
Shoot straight down
Yes, we know we said previously to shoot from a slight angle but if you have a plate bursting with colour, shooting straight down on it can create a shot that's really striking. Just remember to stand up or better still, stand on a chair. We wouldn't recommend you do this while you're out dining though! You could always set up like you were having a picnic too as working on the floor will mean you don't have to go climbing on furniture to get the angle you need.
If you're working with tall items such as ice creams, glasses, bread sticks etc. switch your orientation to portrait as they'll simply fit the frame better and generally, your composition will be improved as there won't be too much space to the left and right of the frame.
Use natural light where possible so if you're at home, set up near a window and if you're eating out, get a seat near a window or sit outside. Also, make sure your camera's built-in flash is switched off as direct flash won't make your food look very appetising.
If the chef in your kitchen at home isn't shy, try and get a few shots of them in action. A candid approach will often give you more interesting shots than if they pose for you so ask them to carry on cooking while you work around them. Hopefully they'll get so carried away with what they're doing they'll forget your there. If you're on your travels, have a look for food stalls where people or preparing, cooking and selling food. The stalls will give you chance to capture some interesting expressions and actions but try not to work up close without permission and don't get annoyed at them if they ask you to move on. Have a look at the ingredients and equipment they're using to see if they're worth a shot or two. Images of interesting bowls, knifes on chopping boards and other every day kitchen utensils can be used in stock libraries or be placed in albums/photo books as fillers around your other holiday snaps.