PSA: When Playing Evelyn DO NOT PRESS R TO KILL (Early in game) + Basic suggestions for item builds

I've had so many kills escape me b/c of that, it isn't worth it, don't risk it. If you have no choice (inc Thresh hook) that's different, you'll die if you stay, so you have to. Early game don't rely on it. Barrier/Heal will quite easily put them above the 30% execute margin, and if they do, then you won't kill them (and will send yourself far, far away).

Your best bet build wise, if you were wondering, would be to go for the Tracker's Knife -> Runic Echoes (she doesn't really benefit all too much from the blue or red smites, though if I had to go for one it would be blue; the slow isn't needed as much do to her reasonably unpredictable paths, you can go through the middle of the lane where the enemy team is if you position right, w/o triggering their red wards to the sides or being exposed), the vision offered from that upgrade is a massive improvement, it allows you to better spot out and assassinate the enemy squishies, and helps you position yourself when moving around to not be spotted or caught out.

After that, I was looking at Liandrys and Rylais, Liandrys and Rylais b/c they stack well together, offer decent AP, good HP (you ARE diving into the enemy team after all, you will die quickly), and this offers a bit more bang for your buck on your Q's and their continuing strikes. Liandry's over Rylais first b/c the pen helps a lot (and the passive is good too). It then becomes more of personal choice, do you want more burst (Lichbane, Rabbadons), more survivability (Lichbane into Defensive item), etc.

There are other builds that should work fine, this one is just personal preference as it has a solid build path, I wouldn't say go straight into Lichbane after Runic, it's not bad (it'll burst hard), but you'll be extremely squishy. Bootwise, don't greed for pen, go for resists (mercs/ninjas), and whatever you do don't go for mobis. Mobis are good at first, until you get into a fight, and can't reach your target, there are so many ways that they can be removed it's not even funny. I found that I'd rather have Ninjas vs a fed AD, Mercs vs fed AP or heavy cc, rather than a bit quicker roaming across the map. Evelyn is hard to track around, she can be pretty much anywhere post-6, you don't have to worry about enemy players reacting to your rotations or being spotted on wards (and therefore wanting to close the gap faster), just saunter on over, and claim your free kills when they appear.

Pro Tips: If the lane is un-gankable, but you want to make the enemy paranoid, randomly walk close enough, pop your W on them, and then walk away back to jungling or off to another lane. They'll likely back off on the pressure on your laner, ping their team and jungler, saying that you're top, and may be tricked into sending resources in an effort to counter a gank that never came; or may make an ill-fated attempt to secure a purportedly unguarded objective or even invade you.

When attempting to take a highly contested objective from an enemy (dragon/baron), read your ult tooltip to approximate it's total execute damage, read the target's MR, and then do a rough calculation on the needed damage to kill it. Add your smite onto the execute range (below 30% ult becomes empowered), and then subtract the damage from your empowered ult (after mitigation by monster). It functions as an extremely strong combination, you can instantly flash, smite, and r back out, potentially stealing the buff, and dealing massive damage, all without exposing yourself afterwards.

Popping W on an enemy you don't intend to go in on, but want to be extremely cautious and warded off the fight (especially while invis in the middle of a teamfight), can be extremely effective. For example, marking the enemy Soraka with my W makes her back off and stop healing frontline, they die, Jinx and Soraka try to flash away to safety, only to walk into my clutches. Buwhahahahahahaha #FeelsBadMan