In their article, they list a lot of great tips for getting the look you want without ruining your lashes as well as some helpful links to products for purchase.
I am a big fan of eyeliner and I didn't even know that an eyeliner pen was a thing! I myself use a soft pencil, but am careful to avoid the lash line so as to not get gunk in my lash extensions. I sometimes use powder, but I just can't say no to a thick and bold cat eye.
What looks do you love with your extensions?