While the easiest way to help prevent kidney stones would be to avoid or greatly reduce the consumption of foods high in oxalic acid, I understand you don't want to miss out on all the other nutrients packed in those foods. While it isn't 100% full proof, some suggestions to help minimize the potential for stones include: Drink plenty of water (fluid) each day 8-13 cups a day - especially before a high oxalic acid meal, avoid calcium supplements (unless a Dr. advised you to) but keep eating calcium-rich foods, keep salt and animal proteins low, cook your leafy greens.
In addition, you can choose to Blast healthy foods that are low in oxalates.
LOW OXALATE FOODS
Fruits: Apples, avocados, banana, cherries, cranberries, melons (cantaloupe, honeydew, watermelon), seedless grapes (red and green), peaches, pear, plums.
Vegetables: Asparagus, broccoli, cabbage, cauliflower, cucumbers; iceberg and Romaine lettuce; radishes, mushrooms, onions (yellow and white); squash (zucchini, acorn, and yellow); red sweet peppers, turnips (root), water chestnuts.
Beverages: Spring and filtered water, chamomille tea, ginger ale, beer, apple juice, apple cider.
Grains: White and wild rice; barley.
Herbs and Spices: Basil, cilantro, mustard, nutmeg, white pepper, saffron, tarragon, vanilla, salt.
Nuts, Peas and Seeds: Coconut; black-eyed peas, green peas, and yellow split peas; flax seeds.
You can read more about it here: http://whfoods.org/genpage.php?tname=george&dbid=48
A good page from Harvard: http://www.health.harvard.edu/blog/5-steps-for-preventing-kidney-stones-201310046721
A great PDF of Dietary Changes to Prevent Calcium Oxalate Stones