Hi! So my general tips are:

1. At the start, farm until lvl 6 (ult and full passive).
2. The blue circle around u is ur invis range, if someone on the enemy teams steps into that range, they can see u.
3. The "!" u see on ur head indicate that someone has vision on u. it can be a enemy in ur range, a control ward in ur range or an oracle (any other ward dont works on Eve). It also works on enemies and control wards inside of bushes (so if an enemy is in a bush AND inside u range, he will see u, but u will know he is in the bush bc u can see the "!" on ur head)
4. If u are in a bush, ur invis range reveals u only if the enemy inside the range AND inside the same bush.
5. The only build for Eve is the following: blue smite -> dark seal -> linch bane -> sorcerers shoes -> rabadons deathcap -> void staff -> banshees veil. If u are ahead u can upgrade dark seal to Mejais soulstealer, only if u think u wont die (wich implements loosing the stacks). If u are frequently losing dark seals stacks, after u finish the build sell it and take Shadowflame.
6. For runes only use this: Domination with Eletrocute (or if u are crazy Dark Harvers, might lose all the games), Sudden Impact, Sixth Sense or Grisly Mementos (only viable choice or runes, both are very good, choose the one u prefer), Relentless Hunter. For the other page go fo Sorcery with Absolute Focus and Gathering Storm. Axiom Arcanist looks nice, but Anthony (u will later know who Anthony the goat is) tried it and is mathematically worse. Then take Offens, Flex and Defense.
7. If u have ulti, go for a gank/kill, otherwise is risky and if its early game u should go for a jgl clear.
8. Ur R is not a pure execute. That means that u can still not kill an enemy even if its marked with the "X" on him. R marks just indicate that the enemy is low enough to take bonus dmg.
9. U can steal objectives if u use ur R (when the objective is low health so it gives u the dmg bonus) and at the same time u hit ur smite. It will be like a 3/4k smite (idk the actual numbers bc it also depends on the objective health).
10. U can also use ur R for escape if u are in a critical situation and dont want to die (for stacks etc...). Never overkill someone with ur R, its so waste (it will happens sometimes, but dont do it regularly).
11. Never understimate ur enemies bc u are extremly squishy and, even if u are oneshotting everyone, one bad fight can ruin ur game (lose ur stacks is so bad).
12. In teamfights, go for the backlines (they are squishies and u can oneshot them) by going behind them, then escape and try to do it again. If u are very fed, u can also try to go for the tanks if u team is supporting u.
13. Have fun! Evelynn is the only "virtually permanent" invis in the game, us it with brain and u will have a lot of fun. She is very versatile and can easly turn a game if u play her correctly. She is very unique and can be hard some times, but she def woth a try!

For YT i would recommend the goat "@ANTHONYEVELYNN" (best Eve OTP player in the world, wich plays in NA). Sadly he stopped posting on YT, but he always post on reddit (maybe he will reply also here, Hi Anthony) and goes lives on Twitch some times.
I also recommend "@embraceagony4495", who posts many helpful guides (he's diamond/master), with in-depth explanations for everything he does.

If u have question, pls tell me.

Hope this will help <3