I get a winter sinus infection followed by a throat infection every year. Antibiotics was the only way to end it or I would end up bed-ridden. But the antibiotics really upset my gut. For the past two years, once I start getting sick, I take high dosages of oregano and thyme essential oil mixed in olive oil, about 100 drops over a whole day. Two or three days of this and it never fully develops. Oregano and Thyme oil…
I used to get sinus infections yearly and get antibiotics. I changed one thing: I stopped blowing my nose. That forces the infection deeper into your sinuses and Eustachian tubes.
Nose picking can also lead to infection, because you're essentially inoculating yourself with whatever pathogens happen to be on your finger.
Aside from avoiding these, the things that have made the most dramatic difference for me is taking Vitamin D and getting flu shots.
Now I virtually never get sick, whereas in the past I'd pretty regularly get multiple colds and occasionally the flu pretty much every year.