So I personally prefer lining with eyeshadow instead of regular liner for several reasons:
1. I like crazy colours.
2. It actually creates a softer look
3. It's easier to create an ombré effect that I find more flattering on monolids (tutorial for super dramatic ombré liner here). I find that a single dark colour tend to look "mask-ish" on monolids or make our eyes look smaller. Using a lighter colour on the inner corner and a darker colour on the outer corner makes the look softer & more natural. If you want a dramatic, dark liner look, I recommend using navy blue or dark brown on the inner 2/3 and black on the outer 1/3 instead of black all over.
The hardest part about lining monolids is actually figuring out how to line it. This is my favourite way of doing it, which I find is most flattering on my eye:
|For maximum drama, line the inner corners & lower lashline with a light, shimmery eyeshadow. Keep your eyes open to get the inner corner placement right.|
1. Following my eye shape, I create a semi-circle that'll peak and peek out of the middle of my eye.
2. Then I'll draw the wing out of the outer corner of my eye, following the line of my lower lash line.
To make it easier to see, here's the side view of how I normally do my liner (I usually do shades of brown for a more work appropriate look, but picked this more colourful version to make it easier to see):
|I love how half my lashes are gone as soon as I open my eyes...|
If you're lining this method, you'll notice your wing looks like it's curved downwards & sideways when you open your eyes. The downwards & sideways ("like puppy dog eyes"), is often called the Korean-style of lining, as opposed to the "American"/"Western" style where the wing curves up. There's a reason this style is so popular in Korea, it's really way more flattering for Asian eyes.