When working on the waterline, you want to make sure not to have such a harsh line. Whether you decide to go over your liner with shadow (which can also work to set your liner) or just blending the eyeliner; your end result a soft, diffused, beautiful blend.
Try this: Urban Decay 24/7 Glide-On Eye Pencil (Shop Now)
Sometimes going from corner to corner is just too bold and can stunt your eye shape. If you want to elongate your eye, bring in a matte or satin shade and then brighten your eye with a shimmery shade added to the inner corner.
Try this: MAC Satin Eyeshadow in Brun (Shop Now)
If the above all seem scary and intimidating, fear not. Adding a swipe of color to just your lower lash line not only gives you a little bit of an edgy look but it will also make your eyes appear wider. Go with bold colored shadows to start and once you're comfortable, ease into adding ones with a little shimmer or sheen so when they catch the light, it will make your eyes look more open.
Try this: Chanel Longwear Powder Eyeshadow (Shop Now)
Although you probably see a lot of people using different shades of blue to achieve this look. Pull out your color wheel and go for a shade opposite your eye color to really get that pop. For example, blue eyes work amazing with an aubergine liner, cobalt blue makes brown eyes pop, and pink is the perfect match if you have green eyes.
Try this: Rimmel London Exaggerate Full Color Lip Liner, You're All Mine (Shop Now)
I like to first start with an eyeliner pencil and then to maximize the liner staying power, go back in with an eye shadow and layer right on top. Depending on what look I'm going for I would either layer a similar shade of eye shadow on top of the liner and blur the line just a bit to set the liner or go in with a deeper color to really smoke out that line a bit.
Try this: Chanel Le Crayon Yeux Precision Eye Definer (Shop Now)
If you're still pushing back on all of the above and you fear of smearing liner, simply opt for a matte shadow which will stay in place much better than a creamy liner.
Try this: Urban Decay Naked Ultimate Basics Eyeshadow Palette (Shop Now)