First of all, get plenty of rest and drink plenty of water. If you feel unnaturally cold, do not attempt to warm yourself up, as an unnatural cold feeling is one of the first signs of a fever. Eat chicken soup and hot drinks (non-caffeinated), raw garlic or garlic powder (for the allicin), as well as plenty of Vitamin C and Zinc.
For a sore throat, you can gargle saltwater or take a cough drop. After your sickness is cured, dispose of your old toothbrush or deep-clean it.
If you need to go out, put on a disposable surgical mask. If you anticipate a lot of content, put on gloves.