I usually have several different cough syrups on hand, that I make. But here are a few that are easy to make that do a really good job, especially with colds:

Honey-lemon: Heat a half cup of lemon juice and a half cup of water to boiling, and add 1-2 tablespoons of honey to it.

Honey-garlic or onion syrup: For the garlic, dice 3-4 cloves of garlic into a cup, add a cup of honey, heat until just boiling, then allow to cool. Take a tablespoon full as needed.

For the onion, dice a small onion into a cup, add honey to fill the cup, bring to a boil, and again, take a tablespoon full as needed.