I'm stickin' with good fats, avoid hydrogenated or partially hydrogenated like the plague. Get plenty of unheated, unprocessed, extra, extra, extra virgin oils with omega 3, 6, 9s. Make sure you have plenty of Zinc, Selenium, Vitamin C, and other complements to the immune system. Exercise helps a lot, moving the blood and vitalizing organs. Avoid too much sugar, it may suppress immunity.
But... here is the important part.
Make sure to make this a lifestyle and routine, consistency wins.
If you're getting sicker, then symptoms are usually due to weakened immune system. It plays catchup and kicks off defending, but the defense comes at the price of symptoms.