How to start storing milk?

I'm going to be working part time within the next month and I want to
start stroing milk for when I'm away. I don't know when I will start
or how long I'll be away. Are there any tips that someone may have
about when to pump or how often so that I can get some milk stored up
for DS? Also, he rarely gets a bottle, I only pump on special
occassions, so he has a habit of refusing and holding out. He's never
been left with anyone but family and only then for no more than 3
hours. How can I get him to accept the bottle more readily when I am
away? Any help would be much appreciated.
Thanx,
Ronika