Playing hard-carry champions that can duel early like Xin are best in silver. The video covers a variety of basic theory you would want to apply in the game which should get you to minimum P5, possibly around D5 ranking.
Lower elo games are also harder to close out, so I would consider playing a champion that can take out towers quickly and effectively while simultaneously being able to thrive in the unpredictable chaos in lower elos. Wukong is a very good pick up.
Always fight for a reason, never burn a summoner unless theres an objective to be gained off of it in the mid-game. Early game is fine because the objective is usually finding opportunities to snowball.
If an enemy uses flash, camp the lane. Pick one lane and beat it down until the tower falls. The advantage you gain will quickly spread across the map like wildfire.