Hi I'm Scorpyyo and I'm a midlane main.
In this guide, you'll be seeing how to play Jayce in the midlane, optimally.
If you follow these guide, I garantee you will be able to climb the ladder.

Let's get more in depht!

This runes will make your early game damage without jeopardising you mid and late game.

Marks:
This Marks will make you hit harder in the early game compared to the AD ones.

Seal:
This Seals make sure you will be tankier in the mid and late game.

Glyphs:
This Glyphs make you harder to get killed in lane, ensuring you can scale into the midgame without many problems.

Quints:
This Quints give you the rest of the early damage to trade and to farm.

Just the standard masteries for Jayce.

The Stormraider's Surge Stormraider's Surge to help you kite and reposition better in the fights,and also to chase enemies.

This Items are the most efficient build you can get.
They ensure early damage, through letality, cooldown reduction, through boots, yoummu's ghostblade and black cleaver, and some survavability on the situational items (GA, Mercurial Scimitar).

You don't level up your Ultimate on Jayce. It doesn't do as much as leveling your other abilities. This also helps your midgame scaling.

You can take the standard Heal Heal, Cleanse Cleanse or even Teleport Teleport.
The first two ensure your laning fases, and the teleport makes your map pressure and midgame stronger, that you can use to your advantage.