Check the package for damage. If the package was cut accidentally, wrap it tightly in plastic wrap and transfer it to a plastic container. If you notice the damage after you get home from the grocery store, don't use it. Take it back for a refund or exchange.
Check the date if it has one. If the date is coming up soon, plan to use it quickly.
Check for any signs of spoilage, and discard the whole thing if it's bad.
Reseal with the original lid if applicable. I like to keep the original foil, if it has it, on top as well to help seal the container as best as possible. If you want to discard the foil, or it doesn't have it, consider using a piece of plastic wrap instead. Keeping it airtight is best.
Use within a week and repeat the above steps each time you open your sour cream.
Notes
You can keep sour cream in an airtight container. Just make sure that it is airtight when closed or covered.