Food photography as Amitai says, is definitely not an easy field. There is so much demand and money in it that the pros perfected it to the maximum. When I tried it before, the results were disastrous and I thought I will never be able to come close to a picture that could be accepted here.
All changed when I bought two of these:
I bought them to try some portrait photos, which came out much better than anything I did before.
But the surprise came when I tried the softboxes on still life.
It is not rocket science. I am not saying I know what I am doing but the outcome is pleasant to the eyes. My wife who does not care too much about my photo hobby (understatement), asked if I could print out the one with the tomatoes. Now it hangs in the kitchen in a nice 8x10 frame. A friend of her ordered two of them for herself and her daughter. (for free..., but I don't mind).
So how did I come up with the positioning of the lights? There is a simple one called Rembrandt lighting
. All you need to do is place the source at 45 deg from the side and from above. Who am I to argue with the old master? Seems to work fine. But it's easy to experiment and try new things. Just move the softbox a bit see what happens.
More things: The image is not going to be sharp without using a tripod. Sometimes manual focus can help.