Tons of sleep and rest. Take everything off your plate you can. Up your vit C. I take L lysine and astragalus through the cold and flu season as general immune support. I take umcka cold remedy (liquid) when I first feel something coming on. A friend of mine who is the director of communications at the health district and very science based swears by it. I also take monolaurin when I feel something coming on.
I’d try garlic and lemon and cayenne mixtures, if I was desperate. I make chai tea with elderberries and rosehips (in addition to black pepper, coriander, cardamom, cinnamon, ginger and cloves.) Green tea or rooibos would be great tea bases for it.
Chicken stock made from a whole chicken carcass (feet if you can find them, they add antibacterial properties)
Colds and flus are viruses and the best you can do is treat your immune system perfectly so that it can focus on doing its job.