Evelynn is a perfect ganker thats why the best place to have Evelynn is in the jungle. With the high mobility she can be everywhere on the map at one time. she can get behind enemy champions with her passive Shadow Walk, and thats why Evelynn is a very good jungler.

Greater Mark of Attack Damage:
Ravage gives you more attack speed AND get more damage from ad and the Hate Spike also gets more damage from ad and in the early game 8,5 extra ad gives a lot more damage.

Greater Seal of Armor:
In the early game even ap-carrys deal a lot of their damage with basic attacks so 13 armor makes you take a lot less damage in the early game.

Greater Glyph of Scaling Magic Resist:
As said in the beginning all champs do a lot of damage with their basic attacks so magic resist is not so important in the beginning but later on many champs do a lot of burst damage with ap so later on you will need a lot magic resist and 24 extra is a good start.

Greater Quintessence of Movement Speed:
Shadow Walks both passive and active gives you good both chasing and fleeing potentials but even with Mobility Boots you cannot get fast enough around the map when you are going to gang a lane and if someone stuns you you will need some extra movement speed to catch up with them.

Greater Quintessence of Ability Power:
Attack damage gives a lot of damage with attack speed from Ravage, and both Ravage and hate spikes gets more damage from attack damage, but in early game it is not very much compared to what you get out of 10 ability power. So it will help you with your early jungling while also havin a little effect in late game. An alternative could be Greater Quintessence of Attack Damage