My house is done in "sections". The family room is the Santa room - we have an artificial tree with only santa or santa hat ornaments (like snoopy wearing a santa hat). On the cabinets I have 5x7 and 8x10 gold framed pictures of my girls with Santa since they were babies (currently the girls are 12 and 14) - I may need to buy more cabinets soon!!! Around the photo frames are little Santa statues, etc. This is my favorite section! I love looking at my girl's pictures!
The buffet in the Dining Room is snowmen on the top, Nuckcrackers on the shelf and a village scene on the main part. A small bookcase has all my Disney Christmas items. The living room has the religious items - nativity scenes, angels.
So what I like is grouping all that stuff that doesn't do much on it's own.
Now, what have I bought in the past years? Greenery and lights! Mostly from Target -- but each year I bought more and all the tops of my kitchen cabinets, computer amoire, staircase got greenery and lights. I also bought funky burgundy and gold ornaments and gold wire bows to decorate the greenery.
Good luck and buy what you like!