When you're laning on blue side, you want to have your champion on the very bottom of your screen and be looking at the center of the screen so that you can see as much of the lane as possible. This feels natural to most people, which is one of the reasons blue side is preferred.
On purple side, you need to do the opposite: Have your champion at the very top part of your screen, with your eyes focused on the middle of the screen. If you started out using a centered camera, this can take a long time to get used to, but it allows you to see everything that's important in your lane so that you can dodge skillshots and be aware of the enemy's positioning so that you know when you can be more aggressive or when you need to back off.
When you're actively engaging, you can move the camera so that you're closer to the center of that if it helps you micro, but for the most part try to keep your champion at the very top of your screen.