express on a with a regular schedule. pump when your baby is having a feed. that's the only way you can let your body produce enuf milk for your baby. nurse baby before work, after work, & before you sleep. all the other times when your baby takes a bottle (say 12noon, 3pm) that's when you express. i personally find hand expresing most effective. if not the Avent hand-pump ISIS is wonderful too. drink lots of water, mother's milk tea (which really helps) & fish soup. of course, enough sleep & less stress also helps with milk production.
when i was nursing my baby, i used to go to sleep latest by 9.30pm after the 9pm feed, so that i can get up to nurse her again at 12 midnight, i get up to hand express again at 3am, wake up at 6.30am to nurse. if you go to work, you nurse her before you leave. then express again at around lunch time & 3-4pm. keep the milk in the fridge at the office or bring ice-packs to keep them cold.
to de-stress, listen to soothing spa music & lie in bed whenever you can.
good luck!