The few times I've expressed I've either done it while feeding (catch the drips while he's feeding, then express properly when he's finished), or while DS is happy.
I put him to the breast for a bit of a drink til my milk lets down, then I'll express. It's alot easier to get more if you get that let down.
I found that I could only get 20 - 40 mls by hand alone, or around 80 mls if I got my milk to let down with him first. My hand & a pump has never worked to get the let down happening.
Everyone is different & expressing may work for the let down for you.
HTH & good luck.