You have to keep updating your buildings. When I started playing, I got a huge culture building that gave me what I thought at the time was great culture. But as you progress, you know that you need to sell those off and replace them with something better. (You can upgrade them, but those huge, early buildings take too many rrs to upgrade, so don't bother.)
You also need to make sure you're only building boosted manufactories, and trading for the rest of the goods. That saves a lot of space. Make sure you keep your buildings upgraded (the manufactories and the workshops and residences). You can buy expansions, but you really don't need to. The trick is in learning to make your city as efficient as possible.