First things first: Evelynn is NOT the best support, but very fun to play and if you have enough experience, you can support the BOT and the MID lane at the same time. Your invisibility makes you able to have "mini ganks" with your ADC, where you surprise the enemy from back.

Your runes are going to be TANKy, because you can use them very well. If you don't have TANK runes, you can also use your AP page, but be aware, that you will be a bit more squishy this way.