Sacrifices that win is lesson 1 of 7 in Real-game tactics 5: Attacking the king, a tactics course suited to players rated around 1400 (club players). Giving material is fine when you get more back. Calculate the line to the end before you let the piece go. It has 7 interactive exercises: 7 calculated lines from real positions. You play every move on a board and get feedback straight away. The lesson is free.
What you practise
Black to move: sacrifice to win.
White to move: sacrifice to win. (6 positions)
Worked examples
Black to move: sacrifice to win. 1...Na2. The quiet Na2 left the opponent without a good answer. The position is winning.
White to move: sacrifice to win. 1.Nc6. The quiet Nc6 left the opponent without a good answer. The position is winning.