Music Index is very similar to RILM.
All the instructions for using RILM also apply to using Music Index (i.e., you can set a limit by language, use the subject tags for precise searching, use the "Find-It" button to find the full text).
The difference is Music Index covers some popular sources, like magazines, that RILM does not. To do a really thorough search, use both databases. You might want to leave out words like "identity" and "social/political" when searching Music Index if you just want to find, say, articles on the artist in Rolling Stone or Spin; magazine writers don't always use that kind of terminology.
You can actually search RILM and Music Index simultaneously. To do so, first get into one database or the other. Then click "Choose Databases" at the top of the search screen.
Then just select both databases from the list.