When you what the common targets are, you should now study the common tactical ideas (patterns, themes) that you can use to exploit the targets. There are many tactical ideas in chess, but trying to learn too many at once can become confusing. Here, the focus is on the most common and instructive tactical ideas that appear regularly in real games.
Exploiting a Pin
Forks and Double Attacks
Discovered Attacks
Skewers
Removing the Defender
Overloading the Defender
Building a Battery
X-Ray Vision
Trapping a Piece
Back-Rank Tactics
Attraction (Decoy)
Clearing a Square
Interference
Capture with Escape
In-between Moves