some information can be found here
One of the most important things to do is appearently to find out the composition of the kidney stones. If this can be achieved, all is much easier because one can then adjust his diet more easily.
If you don’t have one of your kidney stones at hand, you will need to rely on a likelihood approach.
There are several types of kidney stones, the most common type (>80%) being the calcium oxalate type.
Following the Wikipedia link above, reducing the amount of dietary calcium would not reduce the risk of forming calcium oxalate stones, rather to the contrary. Reducing the oxalate by eating more calcium rich food, thereby binding ingested oxalate in the gastrointestinal tract, seems to be more effective.
One should also reduce the amount of dietary oxalate by avoiding the respective foods, e.g. as found here. i.e. spinach, liver, nuts, beans, black tea, chocolate, grapes, red raspberries, strawberries, green peppers and celery.
All these diets are certainly good but one would end up eating nothing or a not healthy selection, so I would rather emphasize on the physics of forming kidney stones, which are crystals. This means that one must avoid that the urine becomes supersaturated so that it contains more solutes than it can hold in solution, so that a seed crystal may form, which can grow and aggregate into a large kidney stone. This supersaturation can be best avoided by drinking a lot and by controlling the color of the urine. If the urine is very thin and pale, then there is no supersaturation. If the urine is thick and has dark yellow color, there is supersaturation. This means, especially in a warm climate, to drink so much that one urinates more than 2 liters per day, better 3 liters.
One should also regularly check the urine with test sticks for blood traces in the urine which are an early indicator for kidney stones.
A final advice can be seen everywhere. Kidney stones are very often developed by immobilized people, such as users of a wheelchair. It is often recommended to do more sports. I have even seen a riding simulator on Wikipedia and one can simulate that by sitting down hard on a wooden chair:
I was also told that drinking alcohol would relax the body so that kidney stones are more easily passed out, but you would probably not find this in the Internet.
Taken all together, it seems to me that playing handball, volleyball, squash or badmington for one hour, with a subsequent beer drinking session (3+ liters), followed by drinking lots of bottled water is the right thing to do. One should eat some cheese before going to bed and put a bottle of water next to the bedside.