I usually recommend using an electric double pump.  This increases the
prolactin level and helps to get the supply up within the first few
weeks, most crucial time.  We have a lot of mothers pumping for their
babies in the NICU.  I find that if they pump every 3 hours during the
day and sleep at night (6-8hours) they do real well.  They need to rest
to decrease the stress and give their bodies a rest.  I find that most of
these mothers end up over producing, which isn't so bad in the beginning
because it builds confidence the milk is there and the mothers can then
drop back to pumping every four hours.  Usually with a double pump they
only need to pump 15 minutes for good results.  I tell mothers not to be
concerned so much with how much they are getting as how often they are
stiumulating the breast.  This is usually very helpful because if they
feel they need to express a certain amount of milk, that adds to the
stress.  We need to work at having the stress as low as possible.  We
have pumps in the hospital with pumping rooms and the mother has a set up
at the hospital that she keeps at the baby's bedside (a double set up)
and they often have a rental electric pump that they keep at home for
pumping.  They don't have to worry about bringing products back and
forrth.  Only the milk and we do provide the bottles and caps.  We have
them use volufeeds to pump into and caps which are supplied by the ABM
co.  They work and the mothers are encouraged to begin breastfeeding as
soon as possible.
Hope this helps.
Darlene Breed RN, BSN, IBCLC