I have 3 Ball Pythons and 1 Burmese python, and have had a 100% success rate thus far using the following method.

Step one: Do not feed snake for 2 months (As long as the snake is a healthy enough weight to fast)
Step two: Holding a prekilled Rat by the tail with tong, keep the rats body on the snakes eye level and jiggle the rat

Ive never had one fail to strike and eat, as long as it was eating regularly first. Ive always give them 1 prekilled rat smaller than an average meal for them would be. I dont try F/T until the next weeks feeding.