The best indexing will depend on what selects you are running, as well as what update/insert/delete activity the tables have.

For a table like this one, you really don't have a lot of choices on the index

If you'll be selecting based on the modified date column, then you'll want an index on there. It would probably include the article column. Again, that only applies if you have enough rows in the table to make it worth indexing, and enough selects with the modified date in the Where clause. If not, then the clustered index alone should be fine.

Other tables will have different indexing needs. It depends on how you use them.