By role, learn the following if you play
Top -
Tank it till you make it.
Mid -
The key to mid right now is not dying. That's it. I mean do moderate damage of course, but don't die for it.
Jungle -

Right now junglers usually decide the game in silver. You want a bully that can win if you ever run into the other jungler randomly, as well as a skirmish champ that can win the 2v2.
ADC -
Really the only one I recommend over others at silver. ADCs are pretty even right now for the most part, depending on team comp. If you were to pick one to main regardless, Cait has the best zoning, which wins the most games in silver.
Support -
These are the 3 gods of supporting. They are each the best in one area, and even though each has weaknesses, they usually aren't exploited in silver.
Here are some tips..
Play defensively until you ward up. Doesn't matter if you think you can kill someone. Just wait two minutes and go get vision. There are exceptions, like for the first 2 minutes of the lane phase or when the enemy team is all visible anyway. But just chill otherwise.
Do not default try to save someone. This turns one kill into two or three or five so often. Run by default when there is no hope, as you run, consider if you can save whoever is caught or dying.
Do not just go back whenever you want. You may have no mana, you may have money for an item. Watch the map first.
Don't be afraid to go off the meta if something suits you. I went ignite top in silver, pretty much every game. Working to your strengths is more important (if they are actual strengths) than following guidelines.