This is my first build! I really like playing Ezreal into basically any matchup. There's no need to try to counterpick an AD carry IMO, just minimize your mistakes. Learn to know the range of Ezreal's Q, as it will help you poke the enemy champs effectively and harass them like Border Patrol does to legal Hispanic immigrants. Basically, poke the enemy team to death.

There's not many choices when it comes to runes for this big boi. Inspiration + Sorcery is standard.

Kleptomancy + Q is your best friend, and will help you rack up that gold quickly to get that advantage over the enemy bot lane.
Sorcery: At this point, I switched from Celerity to manaflow bind because of the switch in celerity. Manaflow bind may help you out if you're prone to firing off that mystic shot whenever it comes up.

Early game:
Try to use your q sparingly, unless you're confident your jungler and support have your back. If that's the case, try to hit the enemy champ as frequently as you can to get that klepto going.

I like to upgrade W next to get that extra burst. It's especially handy when you know the absolute limits on ez's q range.

I save e for last, and use it like I would flash, but not too conservatively.

Try to get a Q > W > R combo when you can and see the enemy champ melt before your very eyes.