If you're lucky enough to have an extra closet or even a couple of extra shelves to store your seasonal decorating items, I envy you. My seasonal items have to be stored in totes and placed in my shed, which I hate to have to do, but have no choice. I simply don't have the room in my home to store these items.
Having a closet to hold seasonal items would make it much easier to change out these items as needed, but I'll make due with my labeled totes,
In any case, it doesn't take a lot of seasonal items to bring the changes of the seasons into your home.
In the kitchen, simply changing out the handtowels, and dishtowels bring about a nice change. Seasonal floor mats also make a big difference. I've also noticed quite a selection of refigerator magnets with a seasonal theme that would help to make the seasonal decor more complete.
If you have a good-sized dining room table, you can easily change the look of it for seasonal decorating. Changing out the table runner for a spring, summer, fall, or winter look is easy to do and inexpensive as well. You can of course accessorize this with colorful napkins and placemats. (Check out yard sales and thrift stores for items - you may be surprised at what you find.) Using a centerpiece of seasonal flowers or foliage for fall will further bring the season to life.
In the living room, some garland placed atop the entertainment center or fireplace mantel using appropriate garland for the season, of course. Replace knicknacks for the season, as well as changing the color of throws and throw pillows, and throw rugs can change the room's look to mimic what is seen outside through the window.
Of course inexpensive window clings can do a lot to bring the feel of the season inside, as well as changing out the wreaths on the doors. The wreaths can be easily and inexpensively made and will welcome visitors to your home.