its from Tim Chapman, one of the best index internal presentation

I will try to highlight the things he talk through this presentation

Indexes

• Clustered vs Non clustered and filtered indexes
• Non clustered indexes and include column effect on index structure
• Heap
• Heap vs Clustered
• Various DMV utilization to understand index internals
• How to detect fragmentation
• Logical fragmentation and effects on query perfromance
• Page splits , Page density, page fullness

Statistics

• How to view statistics
• Effect of statistics on query performance
• effect of stats from index rebuild and reorg

Log usage

• Index rebuild vs reorg
• Log usage for Index rebuilds and reorganize

Over all must watch