I pumped straight into the freezer bags and it was EASY! I used a binder clip (you know, the ones you buy at office supply stores) to give extra security to the bag while I was pumping, but then just squeezed out the extra air and zipped close. Then when I got home all I had to do was lay the bag flat in the freezer and I was good to go. I think I used the bottles that came with the pump twice, and that was the first couple of times I pumped, just getting used to everything. I bought the Lamasil bags, just because I liked those at the time. I think any of them with the zip close top would be good. I just zipped the top closed around the part of the pump that would normally screw to the bottle and put the binder clip above it for extra security. We used the Avent bottles that you just put the freezer bag into. That way all I had to do was send the freezer bags and the bottle and his babysitter just had to heat it and go. No transferring or anything. Good luck!