1. Build for your champion! If your a tank make sure to get more armor, magic resist or health. If your more of a damage champion build more attack or ability power. Make sure to check which one your character is before you start a round!
2. Itemize against the enemy team! If your enemies are stacking a lot of 1 type of damage build the resistance to it (Example: armor for AD or magic resist for AP.). If they start to stack 1 kind of resistance you may want to buy ether armor or magic penetration.
3. Some items are key on some champions! You almost always want to buy some specific items on some champions (Example: Vladimir building spell vamp or Malphite building armor.) Make sure to do some research on the champion your about to play to know what to build.
4. Wards! No matter what item build your going make sure to buy wards. They save you from ganks / give you the ability to organize ganks against the enemy team.
5. Synergy with your team! If someone on your team is building auras and you want to build some make sure to get the ones he doesn't. It works better for your overall team to build different auras because they don't stack more then twice (You and another person with that aura).
I hope these tips were helpful for your overall knowledge of building items in the video-game League of Legends. Please follow and comment with constructive criticism as I am posting more content very soon.
