This experiment was based on the Danbooru face tag page.
1.Main
1.multiple expressions / 2.expression chart
2.Emotions
1.angry / 2.anger vein / 3.annoyed / 4.clenched teeth / 5.scowl
6.annoyed / 7.blush / 8.blush stickers / 8-1.blush stickers, chibi / 9.embarrassed
10.full-face blush / 11.nose blush / 12.bored / 13.closed eyes / 14.confused
15.crazy / 15-1.crazy, :d / 16.despair / 16-1.despair, messy hair, grabbing own head / 17.determined
18.disappointed / 19.disdain / 20.disgust / 21.drunk / 22.envy
23.excited / 23-1.excited, grin / 24.exhausted / 25.expressionless / 26.facepalm
27.flustered / 28.frustrated / 29.furrowed brow / 30.grimace / 31.guilt
32.happy / 32-1.happy, open mouth / 33.kubrick stare / 34.lonely / 34-1.lonely, half closed eyes
35.nervous / 36.nosebleed / 37.one eye closed / 38.round mouth / 39.open mouth
40.parted lips / 41.pain / 42.pout / 43.raised eyebrow / 44.raised inner eyebrows
45.rape face / 46.rolling eyes / 47.sad / 48.depressed / 48-1.depressed, empty eyes
49.frown / 50.gloom (expression) / 51.tears / 52.scared / 53.panicking
54.worried / 55.serious / 56.sigh / 57.sleepy / 58.sulking
59.surprised / 60.thinking / 61.pensive / 62.v-shaped eyebrows / 63.wince
3.Sexual
1.afterglow / 1-1.afterglow, blush, open mouth, heavy breathing / 2.ahegao / 3.aroused / 3-1.aroused, blush

4.fucked silly / 5.in heat / 5-1.in heat, blush / 6.naughty face / 7.seductive smile
8.torogao
4.Smile (smile with mouth close)
1.:d / 2.crazy smile / 3.evil smile / 4.fingersmile / 5.forced smile
6.glasgow smile / 7.grin / 8.evil grin / 9.light smile / 10.sad smile
11.seductive smile / 12.smile / 13.stifled laugh
5.Smug
1.doyagao / 2.smirk / 3.smug / 4.troll face
6.Surprised / Scared / Sad
1.^^^ / 2.color drain / 3.depressed / 4.despair / 5.gloom (expression)
6.horrified / 7.screaming / 8.sobbing / 9.traumatized / 10.turn pale
11.wavy mouth
7.Drawing styles
1.constricted pupils / 2.cross-eyed / 3.wide-eyed / 4.dot nose / 5.no nose
6.chestnut mouth / 7.dot mouth / 8.mouth drool / 9.no mouth / 10.rectangular mouth
11.sideways mouth / 12.split mouth / 13.Yurie mouth / 14.wavy mouth
Thank you for taking a look!