The best place to start your tactics training is in the endgame! Since most of the pieces have left the board, endgame tactics have the clarity that enables you to focus on what is important. In 1001 Chess Endgame Exercises for Beginners, IM Thomas Willemze does two things at once. He explains all the basic concepts, and provides you with a huge amount of exercises for each theme and each chess piece in a highly instructive puzzle rush.