Remember gravity plays a huge factor in where your bombs land. In order to get them to hit their mark you must eliminate as much variance from gravity as possible. The way you do this is to come in from ATLEAST a 45 degree angle. The steeper your angle of approach the better.
Obviously coming in at that angle is easy. it's pulling up in time to be acurate but still keep from crashing that most people have problems with. This is when you need to use predictability to your advantage. Pick a spot that your target is moving towards. Just time them to land in that spot the same time your target gets there. Remember the faster you are going, the faster your bombs will fall. But more so than anything it really takes practice and an ingrained sense of what the bombs will do when you release them that gets you kills.
Obviously coming in at that angle is easy. it's pulling up in time to be acurate but still keep from crashing that most people have problems with. This is when you need to use predictability to your advantage. Pick a spot that your target is moving towards. Just time them to land in that spot the same time your target gets there. Remember the faster you are going, the faster your bombs will fall. But more so than anything it really takes practice and an ingrained sense of what the bombs will do when you release them that gets you kills.