1. If you're a girl I suggest you take the pill. Either Diae (also sometimes named Diane 35 or Dianette) or Yasmin. Both are perfectly good contraceptives, but are also used for acne. I've been on Dianette for 3 years myself. It's a long-term thing. The effects won't start showing after quite a long time (at least 6 months I think) (read more about this pill here
http://www.netdoctor.co.uk/medicines/100000754.html
2. Use a very gentle cleanser. Currently I'm using Clarins Purifying Cleansing Gel for oily skin. I really like it, and have heard nothing but good stuff about the Clarins products, so I think I'll soon start using some of their other products as well. It's a bit on the expensive side, but worth it. If you don't want to spend that much money I also suggest Cetaphil for normal to oily skin. Very lovely cleanser as well and cheap. (available at drugstores, I used to buy mine at Walgreens for like 5 bucks)
3. TONE! I use a completely natural toner: rose water. I love it. I think it's good for all skin types. Witch hazel is also very good for acne skin. Tea tree oil toner is also a good option for those with oily skin, just make sure it's not too concentrated. Pure tea tree oil can also be used as a spot treatment btw. You can buy it at The Body Shop, or other health stores/natural food stores (such as Whole Foods)...
Another good toner is green tea. Make a cup of green tea, allow it to cool and apply to face with a cotton ball. Only do this at night though, because it can give your skin a weird color (but that will wash right off in the morning!). This really calmed my skin when my acne was bad, and made my face less red. Another good toner is apple cider vinegar, if you can stand the smell....it's pretty bad
4. Treatment/Moisturizer. Alright, I've read a lot of times that even oily skin needs a daily moisturizer. I don't do this, unless my skin feels really dry. I do use pure aloe vera overnight, which is considered a moisturizer. I see it more as a treatment since aloe vera has helped me A LOT. It soothes your skin, makes it more even toned and soft, dries up blemishes.....and FADES ACNE MARKS. seriously, best thing I've found for my scars. It's amazing how much they've faded. You have to use it every night though! I bought a huge 24oz bottle of Fruit of The Earth Aloe Vera (100% pure) at Walgreens for a few bucks and I've been using it for the past 6 months and it's still not empty!
THE FOLLOWING IS FOR PEOPLE WITH ACTUAL ACNE (moderate to severe):
If you are still in an active acne stage then you'll probably have to use a treatments from the derm (or a drugstore OTC treatment). I've tried them all and even though I love that I am now able to treat my skin with gentle, mainly natural products my skin would probably ot have gotten like this without the helps of some of the things my derm prescribed. I've tried them all: Differi, Acneryne, Benzaclin, Tazorac.... the Tazorac is awful at first, because it seems to make your skin worse and you get all red and shit. But it helped me A LOT, you realy need to keep on using it until you get past the bad phase though...which is very hard

It also fades marks and scars. I also like benzaclin as a spot treatment (don't cover your entire face, cos it'll dry you out).
ANTIBIOTICS: yes, sometimes it's really necessary. I've been on a few kinds. Minocycline worked a little but my acne returned. Tetracycline didn't work at al for me. Doxycycline (I took Adoxa) worked great for me. I took it for
7 months I think, but after 4 months instead of 2 pills per day I only took one. I quit taking them 3 weeks ago and the acne hasn't returned yet luckily.......we'll see.... I suggest seing a derm if you have pretty bad acne (ot just blemishes, there's a difference between having some pimples and having acne....People are fast to say "oh god. i have acne" while in fact it's just some small breakout.)
5. MASKS: every other day (or less) I use a mask. I like The Body Shop Tea Tree oil mask, because it cleanses my skin and takes away any redness (it's amazing). Also: Queen Helene's Mint Julep mask. Really cleans out pores, reduces blackheads, shrinks pores... Also great as an overnight spot treatment.
I also like the Aztec Secret Indian Healing Clay. This is a completely natural clay powder you mix with water or apple cider vinegar. You put it on and it dries and you can actually feel your face pulsate as the mask gets all the crap out of your pores. your face will be a bit red afterwards, but that fades in a few hours. Egg yolk is also a great mask. just take an egg yolk and put it on your face for 20 minutes. The story behind it is that it's full of vitamin A and for example, Accutane (very strong acne medicine) is a derivate of vitamin A so the egg yolk is like topical accutane. I don't know whether this is true, but the egg yolk calmed my acne a lot back when it was very bad, and it's good for your skin in general.
6. NUTRITION
I know there's no scientific evidence that diet matters when it comes to acne, but I switched to soy milk after I started to notice my skin would become worse when I had milk. and in fact, now, when I do drink regular milk, I will have zits the next day! so yea, try to find out for yourself what doesn't work well with your skin, every person is different. I also can't eat too much chocolate cos it does break me out.
7. Microdermabrasion: only when your acne isn't active any more! I started using the Olay Regenerist Microdermabrasion kit once my acne was practically gone. It evened out my skin tone, and helped fade marks and scars. I love this. Also very nice if you get flaky skin from the acne products.
umm....that's about it I think. Hope this helps someone!