I exc. expressed for different reasons a few times (DD1 had jaundice and didn't ebf until 8 weeks/DD3 had bronchiolitis multiple times and I was in hospital at different times when DD3 was small too).
The things I have found that work for me are:-
Expressing every two hours, including at least once between 12-3am so you get 8-12 sessions in a 24 hour period (a longer stretch over night would be ok once supply is established)
Massage breasts before starting to pump (towards the nipple)
Breast compressions during pumping can help too
Double pumping - can make hands free by clipping bra back up or doing this
Not looking at the bottles - even covering up the whole pump with muslin/pulling top back over the pumps
Distraction - read a book, play with baby, make a phone call to a friend, watch TV, MN....
Block pumping once a day - pumping both sides for 10 minutes, resting/reading book/going for a walk/what ever for 10 minutes, pumping both sides for 10 minutes, resting for 10, pumping for 10. This is a technique designed to mimic cluster feeding in baby and really can boost production so don't worry about how much milk is made by doing this it's the signalling to breast that is what's the point.
Drinking to thirst not X litres of water a day (sorry flaurenoko - drinking water to excess is linked to lower milk supply not greater)
Looking at baby when I expressed, smelling a babygro, looking at a picture of baby
Thinking of waterfalls of milk coming out of my breast - weird I know but it did help at times.
Hand expressing as soon as I have stopped pumping - this seems to get the 'last' out. Not that breast are ever empty but this seems to get that little bit more out.
If baby is full term and healthy, you don't need to sterilise the pump each time you use it just once a day. You can place the pump flanges (breast parts) in a zip lock bag and put it in the fridge until next time or rinse out with very hot soapy water and air dry. The bottles/teats should be sterilised though.
This is a good site for exclusively pumping/expressing mums here.
Good luck and I hope it helps.