Choosing a nice well drained spot for your bulbs helps. Bulbs don't like to soak in wet ground--they will rot. I used to put some loose soil & peat under the bulb. I don't anymore since it seems to encourage my holes to hold water around the bulbs.
Plant your bulbs 2-3 times deep as the height of your bulb. Too shallow seems to be better than too deep for me in my clay ground. Tractor roots pull the bulbs down as the bulbs get older and larger.
