Considerations for Adding Indexes to a SQL Server Database
If you can review the suggested indexes and maybe try adding a few here and there. However, be cautious of over-indexing. Over-indexing can cause SQL Server to get confused on which index to use and that can lead to "DUI’s", that is, it can hamper the performance of Deletes, Updates or Inserts (DUI’s). Also look up the concept of a covering index. A covering index is a single index that "covers" the query and that index can also be reused by other queries, effectively reducing the number of indexes needed.

Watch this excellent free 30 minute video by Kendra Little that covers Indexing in SQL Server:

https://www.youtube.com/watch?v=wAhr91FBlx4