When I feel blah about the house, I just flip thru various web sites, and get inspired.
Problem with my house is that, for some reason, our furniture, as we moved in, fit exactly one place in the house,
and nowhere else. A friend of mine with good taste pointed out the places for the unloading crew to put stuff,
and I have not moved it in 10 years..it is perfect as is.
First and only time that has happened.
A general hint is to make a room/area look balanced in terms of furniture size, groupings and colors.
It takes a lot of stepping back and looking from different angles.
That is why looking at room design pics is a good place to start..you know immediately what "look" you like.
Me, I am more of a English country person, which is a look that is common down here in the South,
along with greenery ( plants, ferns, fabric,) in the house, use of shutters, lots of white in trim and curtains and etc.
I would start with what style you like best and then look at examples of it, closely, so you can see what attracts you.