acne is no fun at all; your face is your main way of interacting with other people, so any problems with it can feel a lot more serious than other defects. here are some things i've read about / experimented with for reducing acne.

1) eat as natural as possible (fruit, fish, nuts, vegetables). our bodies are adapted to natural foods, while modern food makers will often engineer food to be profitable rather than healthy (or they just won't realize that the food is lacking some important elements; the ways foods interact with our bodies are pretty complicated while the ways people evaluate whether to eat a particular food are fairly few). i've read that china is seeing way more acne now that their citizens are starting to adopt a western diet. stay away from grains, especially refined carbs (breads, pasta), and avoid high-fructose corn syrup or anything else that makes drastic changes in your blood glucose levels. you don't have to be a nazi about it; if i'm craving lucky charms or a bagel, i buy it. and i drink tons of milk even though it doesn't quite fit into my theory. i'm just saying that i think there's probably a correlation between eating natural and having fewer problems with your skin, so i try to get most of my calories from natural stuff. i've just recently started to suspect that a lack of natural fat (nuts) in my diet may have been causing problems for me in the past.
- There's been a trend among dermatologists to say that diet doesn't affect acne; even if you go to acne.org, which I once thought was a great source of information, the guy who runs the site (Dan) seems undecided about a connection (http://www.acne.org/diet-and-acne.html). While I'm sure there are probably a number of different causes for acne and some people would not respond to changing their diet, I'm becoming more and more convinced that diet is extremely important. The study below talks about the connection between the glycemic load of one's diet and acne:
"Implications for the Role of Diet in Acne"
http://goo.gl/xCZeQ

Here's a good example of an unnatural diet causing problems in other animals:
http://www.squirreltales.org/#Section-H

2) get enough vitamin A; i get it from carrots, liver, and spinach. vitamin A is important for your skin, and the most effective existing acne treatment (accutane) is just high-dose vitamin A. most people don't get enough vitamin A because they eat engineered food. my preferred way of getting it (i.e. it involves the least work) is those 1lb bags of baby carrots; chicken / beef liver is my second favorite way.
- Below is a great article on another vitamin deficiency that people didn't know about for a long time; after reading it I feel more confident that vitamin A deficiency could be causing problems that aren't being given much attention. Excerpt: "One of the most striking features of the disease is the disproportion between its severity and the simplicity of the cure. Today we know that scurvy is due solely to a deficiency in vitamin C, a compound essential to metabolism that the human body must obtain from food. Scurvy is rapidly and completely cured by restoring vitamin C into the diet."http://idlewords.com/2010/03/scott_and_scurvy.htm
- Below is a study which found that 1) people with acne tended to have lower blood-levels of vitamins A and E than people without acne, and 2) people with worse acne tended to have lower blood-levels of those vitamins than people with less-severe acne. "Does the plasma level of vitamins A and E affect acne condition?"
http://goo.gl/C2XR3

3) avoid having anything press against your skin, especially if it's sweaty or greasy (hands, dirty pillow/bedsheets, dirty goggles, phones, etc). i can say with confidence that i've seen this cause acne.
- ex: i've seen acne show up precisely where i had (presumably sweaty) snowboarding/skiiing goggles pressing down on the bridge of my nose; from having the strap of my bicycle helmet pressed hard against the sweaty skin behind my ear; from a heavy backpack pulling its straps against the skin of my shoulders; from leaning my head on my phone; from having bangs when i was a teenager; and people are far more likely to have acne on their back (where there's lots of sweat and friction from your shirt) than on the front of their bodies.
- at the moment I use a new white t-shirt or pillow case as a pillow case every night (real pillow cases are too expensive to get 10+ of them). I try to wash my sheets every week to get any sweat or dirt off them.

4) get enough sleep, avoid stress, and get enough calories. if i'm lower on calories or stressing about something i will reflexively/unconsciously pick at my skin. after thinking about this some more i'm wondering if it's cortisol in my blood that's causing this, as I've noticed the same feeling after intense exercise (which also triggers cortisol release):
http://en.wikipedia.org/wiki/Cortisol

5) if you have acne around your mouth, try going a week or two using baking soda instead of toothpaste and see if the acne goes away at all. i've read that the foaming agent in toothpaste can be a skin irritant and cause acne. i think i've noticed a correlation between using toothpaste and acne around my mouth, but i'd need to experiment more to be more confident.

Rosacea

the more-severe-looking acne you see out there is usually rosacea. I've never had rosacea myself, but i'm curious about what causes it, so i'll post links / info i find here.
the link below discusses a study in which 96% of those people who were given an intestinal antibiotic had the rosacea go into remission. the comments below the post are even more informative.
- http://rosacea-support.org/sibo-eradica ... rious.html
here's a forum post in which someone claims to have cured their rosacea with vitamin A:
- http://rosacea-support.org/community/vi ... php?t=2334
I didn't know this until i read the wikipedia article, but apparently JP Morgan had rosacea and was very self-conscious about it: http://iconicphotos.wordpress.com/2009/ ... tographer/
The person in this thread said they cured their rosacea in two weeks with the topical antiparasitic invermectin, the photos are extremely impressive: https://www.reddit.com/r/Rosacea/comments/hpp9tn/2_weeks_into_the_horse_paste_and_my_type_2_has/

Other Skin-Care Advice

Apparently Robert Pattinson used SK-II (a skin product) while shooting Twilight:
http://www.youtube.com/watch?v=HBpNps3xATc&t=2m55s

Misc observations

Fiber in your diet (via broccoli, carrots, flax seeds) apparently slows the rate at which your body absorbs sugar:
- https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

Articles

http://www.nytimes.com/2016/10/21/well/eat/yes-foods-may-fight-acne.html

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