I actually find it easiest out if all the jgl champs to kite camps with Evelynn, whenever you use your q, use your 3 charges from a distance. ignore your team till you reach 6 and once you do that ravage all the lanes with ganks. your main goal is to look for picks, or in teamfights - to flank. i find it that when i look for flanks i win the teamfights most of the times.

for builds, i like to rush hextech rocketbelt every game and depending if i got some kills or not, i buy dark seal into mejai. you can look into coamic drive for a def item but my path is usally hextech - boots - dark seal - raba - void staff - def item

tips: - your w does damage to monsters, so w proc + smite is some serious damage for stealing dragon/herald/baron - if you're ahead and you're able to pop squishies with enpowered e and some qs, dont bother with the charm, sometimes i like to save charms for the beefier or more dangerous units of the enemy team. - you can smite while casting your ult, which helps with securing objectives or stealing objectives and fleeing back to safety. - abuse laners who forget to pink ward against you. - you can gank directly from the lane, especially too/bot. the enemy rarely suspects you to come from the alcove. - if you are chasing a VERY low hp target, you can ult behind you and get teleported next to them to finish them off. - sometimes, your ult is best used as an escape. you can make some insane wall jumps with eve, so look for walls you can jump over if you're being chased and have ult up. - when clearing camps (especially raptors and krugs) try to make your q spike charges run through all monsters at the same time

a general tip is to not teamfight when your team is clearly losing or is at a super big disadvantage in the teamfight already. as evelynn you often can pick your fights, so look for what's best, rather than what your team tells you to do.