King safety

Always consider the safety of your King before opening up the position. In the diagram below Black is already in trouble and he opens up more lines to his own King with: 

16. ....cxd4?. Then it goes downhill fast. 

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16. ...cxd4?
17. cxd4 Bg7
18. Rc1 Bxe5
19. Bxe5 Rd7
20. Bxh8 Ne4
21.Qa8# mate

Lesson: open up lines to the enemy King when you're attacking NOT when your own King is under pressure.