Doesn't matter what I cook, I always like to double or even triple the recipe so I have leftovers. They're so good to pop in the freezer and save for a quick lunch or dinner, to avoid the dreaded takeaway or for the times when you or the children are sick or you just can't be bothered.
I'm a big fan of ziplock bags and for something like soup, I grab a coffee mug, insert a ziplock bag and ladle in the soup. The coffee mug is a perfect size as you can reheat in the mug and eat from that. Just zip it up and whack in the freezer. The ziplock bags don't seem to take up as much freezer space like a plastic container would.
For lasagnes, pasta bakes and similar dishes, I just cut into a serving size and pop into the ziplock bag. Throw it into the microwave to defrost and cook and you're done.