You can fundamentally decorate a living room for free; even in case you have a specific theme or style in mind. For a cottage look paint all of your furniture with a distressed finish & paint the trim a bright white to give it new life. Then you can bring in crisp white curtains & then balance them out with some bright white accessories. Florals can be present in thrift stores & online classified ads because they are not the typical modern sofas. This will give your room a distinctive look that is feminine while the same time staying true to your budget.
You might just be working with this same neutral couch that seems to be in so many homes. A lot of new construction homes lack character and architectural details. This is why you really need to focus in on pattern and color to add some life to your living room. One of the least expensive ways to do this is with throw pillows. Yes, this is very common way of decorating that you can do in nontraditional ways. Try mixing a lot of different patterns and colors to really liven up a room. You could pair purples with red and blues a very lively and powerful look. You can try mixing different geometric prints and patterns to really make a statement in the room on a budget.
Gather your collections together. This will help reduce the look of clutter and will also showcase your favorite items in the room. Try hanging smaller pieces of artwork next to each other so they really have a dramatic impact that you can appreciate. This will update your favorite items in the room and also turns them into the focal point.