trans upgrades?

i am looking for some upgrades for my trans. i already have a conv. and valve body work. want to know what i can do to make the trans hold better/stronger. some people have said it need more pressure and other tell me it needs electronics? is there a programmer for the trans or what do i need to do? i would also like it to shift alittle harder. help me out guy i need to tell the trans guy in the morning so he can order the stuff i want