As you prepare for your move into a smaller space, the first thing you need to assess the amount of space your current home has in comparison to the new home you are about to move into. If the entire living room will fit in the new, great, but how many closets are in the new space? How large are they? Does you new unit come with a storage locker in the condo building? How large are they? Does your new unit come with a storage locker in the condo building?? What is its size? And how does all that space compare to the space in your old home?
Going thorough all this in advance will give you a good idea as to how much space you will be losing in the new house. When you know that, then you can start determining what items the new home will not have space for, and this will give you a clue as to how large of a self-storage unit you might require.