Getting a kill is not enough
I recently watched a friend play a Bronze ranked match. His team won 56-21. The match lasted over 40 minutes. While watching them I noticed something... They would get a kill and then accomplish nothing else. A player would get a kill and then base or the team would get an ace and then base or farm. Sadly, I now notice this in Gold as well. I see it all the time...
If all you get out of a kill is that kill then you are not doing it right. If you kill your lane opponent then use their death time to push the wave to their tower before you base. Why? They lose the exp and gold from the minions and your minions will get damage on the tower. If your team wins a teamfight then use that to your advantage. Ward the enemy jungle. Steal enemy buffs. Take dragon. Take baron. Take towers. Take SOMETHING. Don't just base and buy or farm.
Please, get more than a kill out of a kill.