Basic Index Tuning using DTA (Database Tuning Advisor) to indentify indexes that need to be reviewed and validated against the current workload of your T-SQL queries.
Advanced Index Tuning using a Query Execution plan to find missing indexes and determine the expected percent of enhancement for expensive queries.
This method offers the benefit of simplicity as well as detailed reporting and a broad scope of tuning options which can include indexes, filtered indexes, indexed views and schema partitioning that it can’t be covered easily by the advanced method.
Start Analysis and then you will be shown the DTA recommendations and report.
Index scans can result in major performance degradation and high CPU utilization as it reproduces CXPacket waits due to insufficient indexing that cause a query to scan the data entity of tables instead of seeking the indexes. Therefore we should create the appropriate non-clustered indexes to replace all index scans by index seeks using covered compound indexes.
Covered compound indexes are normally the most efficient way for indexing since they comprehensively cover all table columns that exists within your T-SQL queries and thus can replace index scans with index seeks.
If your databawse operations are inclined more to OLTP transactions (Insert/Update/Delete) rather than Select queries then large non-clustered indexes sizes can impact negatively OLTP performance as it will increase the size of clustered index and thus the IO cost.
Table scans take place in cases of a missing primary key, so you have just to create primary keys on the appropriate columns of relevant tables.
II.	Filtration criteria should have the same syntax as the relevant query itself .
Data Compression and more especially page compression where a significant reduction of I/O cost can be achieved (row compressions can be better sometimes but to estimate which is optimal you can run Exec USP_Compression_Savings_sp results (Attached with Article) to show clear estimations about compression savings for each).