I love to use what nature provides. We have fir and pine trees. Cheap, beautiful and it makes the house smell wonderful. I use cut branches on my mantle and tuck in ornaments in what ever color I like (red, green, gold or blues and silvers or golds and silvers). The dollar store has glass ornaments and often you can buy on clearance on Dec 26th. I put cut branches in a clear glass vase and tie a bow or ribbon on the vase for another decorating idea. You could make a wreath or a swag for the front door. My MIL uses real evergreen on her dining room table. Pine cones also add to the look.
Instead of buying Christmas gift bags (if you didn't buy them on clearance the year before), use brown paper bags from the grocery store. I use leftover wrapping paper scraps and paste the scraps over the side with the store name. The bags are large enough for the big gifts that would be awkward to wrap,too. As a filler for my gift bags, I run scraps of wrapping paper through my shredder and have colorful filler. Good to use in place of tissue paper, too.
For gift tags, I use last year's Christmas cards. I save the cards for one year (I keep them with my decorations) and after I look through them again and finalize my card list, I cut the front of the cards off and use those for my gift tags or paste onto plain gift bags for a Christmas look. I recycle the other parts of the Christmas cards.
The only time I bake cookies en masse is at Christmas. I usually do a big batch of sugar cookies and either roll them in colored sugar prior to baking or make red and green frosting and let my boys decorate them. Sugar cookie recipes range for very easy to lots of ingredients so a simple recipe is easy to find. I usually just do round cookies but you can do the roll and cut out with cookie cutters bought at the dollar store.
Soups are easy and frugal. We usually do a soup meal on Christmas Eve and I invite all the family over after 5:00 church for soup and breads/rolls. Easy to make ahead, keep warm in a crock pot and goes a long way.
My BIL and SIL and DH and I have decided to forego giving each other gifts. We have more than enough "stuff" and give the gifts for the children. Each child receives one $10-15 gift ( I have 4 nieces and nephews).
I look forward to reading other ideas!