Sing it with me! (Just a little bit.)
One of the most common lane mistakes I see is one player not respecting the potential of the opposing champion.
This is a simple idea. If you truly know the match-up, you probably understand the damage trading potential of the champion you are laning against with this champion. Again, I need to emphasis that it isn’t enough to play Gragas vs Fizz one time and say that you know the match-up. As skill level with a champion varies, you may win damage trades in unfavorable match-ups, simply because your opponent doesn’t know how to play their champion well. Don’t assume that playing Gragas vs Akali a few times is probably close enough as a comparison because every champion spikes at different points of the game and has unique tactics to achieve optimal damage trades in lane (doing the most damage to you while taking the least damage.)
You should always respect your opponent’s capacity to inflict harm on you. When you don’t know a match-up, you need to be even more thoughtful.
Well. If it is not a ranked game, feel free to go ham and explore your own capacity to do damage to them. Expect everybody on your team to be a little irritated with you if you lose your lane, but you’ll gain a lot of knowledge by testing your own limits. Your opponent may play passively in response to your exaggerated aggression. Eventually, you’ll hone your play with a champion to know just how far to really go without going to far.