The diew may give a better roll if it thinks it's for somebody other than you. Before rolling a die, pray to whatever god you wish to guide the die. Before rolling a die, kiss it. If the die is sentient, it will know you care and thus give you better results. Before rolling a die, burp, fart, or do some other disgusting thing to it just to show the die who is in charge.
Humiliation is great incentive for a die.
Before rolling a die, place it in a body cavity such as an ear, nose, mouth, or worse. Then you should begin to tremble while humming before releasing the die. This will charge the die with your own personal postive life-force energy. Before rolling a die, twist it so that the positive energy is squeezed out to the sides where it is need most. Before rolling a die, the longer you shake it the more random the result.