Appreciate the fact that you are getting dominated and realize it for what it is: You making mistakes that you need to correct.
Once you understand this you begin to pay attention to how your opponent is laning, what they're doing that causes them to win trades, as well as how they are countering you. Once you realize a certain tactic isn't working against this player, you try new tactics. When those begin to work you fine-tune them, making them automatic. This is like "advanced improvement," because your mistakes look so glaring.
Here's what you do. Play a game with the intention of getting dominated. Do your best, but go into it knowing you probably won't do that well, which is the point. start paying attention to what happens and why you get dominated. Then come back here, and point out what happened in lane, and advanced players (ExecutionerKen for instance) can point out flaws in your gameplay and things you can improve.
An example from my own experience is me as Lee Sin laning against a very much better than me Nunu. He threw an iceball at me and a couple of auto-attacks at level 1 and had me zoned from the beginning. I asked him later how I could have prevented the zoning and he basically said "You can't. What you do is start with W (Lee's shield) and then harass back, instead of starting with Q and attempting to outburst me." So I needed to reduce his burst and then engage, instead I was engaging during his burst and not really reducing it.
It may not be as efficient as having someone play a few games with you but you'll get more responses that way. Good luck.
EDIT: People tend to rage pre-30 about normals because they haven't done ranked. If people at level 30 are still raging just pity them. Normals are so ridiculously relaxed. They're used to wind down after a couple of frustrating ranked games. Don't let it get to you, use normal games as your practice arena, your learning time, and don't be afraid to lose in order to learn. One thing I honestly suggest is taking a champion and going "all-in" against whoever your laning with to understand their burst and what they can handle. Sometimes it'll cause you to lose the entire match, but it's great experience for the future - you'll know not to all-in a Jax as Darius, for instance, because Jax actually beats him, or you'll discover that you can all-in a Karthus as Fizz, as he'll get melted at any point.