You could use blue and silver decorations, that would look nice
You could make it really fun by decorating with light-weight cars and trucks or other small miniature toys that he likes such as dinosaurs, etc. . Maybe add thin rope or colored twine in his favorite color for garland. Lights in clear or again in his favorite color.
First make sure the tree is more than two feet away from the baby. Even an infant can get his fingers or toes strangled by tinsel or wires for lights. If his hands can reach any part of the tree, he can pull it over. Use lots of twinkly lights. Ornaments can be swallowed if small enough, especially if they fall on the floor. Other than that, you can get tiny ball ornaments. If he is old enough to like a category of things, just shop the inexpensive toy aisles to find bags of dinosaurs, farm animals, zoo animals, wild animals, dogs, soldiers (without separate rifles or swords), animals of the savannah (elephants, zebras, giraffes), snakes, angels, bells, etc. etc. and bows and garland. I love a Christmas tree in every room, but babies can find a tiny pin in a huge carpet, swallow it, and start bleeding with no clue you can identify, so be 10x careful. Actually, lie on your stomach in his room and start feeling of every inch. What you don’t find, the baby will. Merry Christmas!
I think Buffalo Plaid is nice for a boy. How old is he? That might make a difference. If he is older, he might prefer a favorite toy theme.
Omg, I love this! You can buy one of the smaller 4.5 ft. trees - they're fairly inexpensive (bought mine last year for my apartment) and can be decorated with $10 lights and $10 of ornaments. For a boy you can add in a Polar Express, electric train set w/ locomotive engine sound!
Silver and blue would be perfect.