I tend to 'batch-cook' once a fortnight or so as I still can't get used to only cooking for 1, and it is hard to get anything in single portions.
I use my plastic tubs, but lined with a freezer/sandwich bag. Pop the food in the bag (that's in the tub), into the freezer un-sealed, then, when it's frozen (usually the next morning) I just pull the bag out of the tub, seal it up and pop back in the freezer...that way I have the tubs still free for the next lot!
I currently have chilli, liver and bacon casserole, tuna pasta bake and meatballs and spaghetti in there...soon to be joined by sausage casserole and shepherds pie(well, the mince part of it anyway).
I've also found the little foil tubs with cardboard lids that you can get are good. Can get a pack of ten for £1.50 in my local sainsburys!