Hitting an enemy who sidesteps your skillshots?

• Anticipate where your enemies tend to sidestep to. That's how faker landed his spears back then.
• Forcing your enemy into a situation where dodging isn't possible, ie next to a wall.
• Fire your skillshot when your enemy is in the middle of skill animation (caitlyn q for example).

And lastly, my best advice...if you can't land your skill shot, then don't use skill shot. There's no rule saying you have to make challenger play and land your skills from max range. Just walk up to your target and use your skill at point blank. Lots of go up to knockup targets before they pull, and lots of walk up their faces before using q to stun.

Shoot your skill shot to the side instead of directly on them

You gotta predict the prediction lines.

when you notice they are dodgeing a lot try to notice patterns

Example I am morgana, I throw binding, they dodge left I am Morgana, I throw binding again, they once again go left

Where will they go if I do it again? I think I am noticing a pattern here

Not really something you can teach, just mind games you gotta learn from experience.

Your options are

1. Get closer (not an option for many)
2. Follow up on other CC
3. Predict enemy movement

If the player dodges everything, there is a chance he/she is scripting