Tactics
Attacking with check
Any move that gives check and attacks something else wins the something else, because check is not optional. It is the same idea as a fork, said the way it actually turns up: not two pieces lined up neatly, but a check that happens to hit a loose rook on the way.
How to spot it
List your checks. Every one of them, including the ones that look like they lose a piece, and then ask what each one attacks besides the king. This one habit finds more material at club level than any other, because it costs no calculation at all: the check forces the answer and you take the rest.
The positions
Easiest first. Every one is from a real game, and the rating under each board is what it costs the players who have tried it on lichess.
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1. White to play Play it out →Answer
39.e8=N+ Kf8 40.Nxc7
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2. White to play Play it out →Answer
27.Nc6+ Ke8 28.Nxd8
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3. White to play Play it out →Answer
32.Nf6+ Kh8 33.Rxh7#
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4. Black to play Play it out →Answer
35...Qa2+ 36.Kf1 Qxb1+
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5. Black to play Play it out →Answer
11...Qa5+ 12.Bd2 Qxb5
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6. White to play Play it out →Answer
17.Qxd8+ Kxd8 18.Nxf7+ Ke8 19.Nxh8
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7. Black to play Play it out →Answer
26...Qxf2+ 27.Kh2 Qxd2
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8. White to play Play it out →Answer
39.Be6+ Kf8 40.Bxa2
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9. White to play Play it out →Answer
15.Qa4+ Bc6 16.Qxd4
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10. Black to play Play it out →Answer
48...Qxg3+ 49.Ke3 Qxe5+ 50.Ne4 dxe4
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11. White to play Play it out →Answer
48.d6+ Kd7 49.dxe7
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12. White to play Play it out →Answer
44.Rf7+ Kg4 45.f3+ Kg5 46.Ne6+ Kh6 47.Nxd8
Reading about a pattern is the easy half. Motify finds the positions where you missed one, by running your own lichess and Chess.com games through Stockfish, and puts each of them behind two or three puzzles on the same idea so you meet it having just found it three times. See how Motify works.
Positions from the lichess puzzle database, released under CC0.