I'd highly recommend getting your hands on an electric pump if you can - a medela swing is a great one
I had a manual pump for DS, and I had mixed success pumping. I used the medela with DD and was able to express about 3-4 times what I could with the manual one

A few other tips to try
- Dont express when you are tired, I could never get my boobs to come to the party then, especially late in the day. I'd always express first thing in the morning and mid morning
- Make sure you are drinking lots of water - good for maximising milk supply
- I always found if I expressed about an hour or so after DDs last feed my supply had replenished so I'd get a decent amount, and then had enough time to produce more milk for her next feed.

HTHs