I see a lot of people here asking what to look at to treat acne scars/marks.
Admittedly I've had severe cystic hormonal acne from age 13 onward; Accutane is all that help and even with four years on Aldactoneand being on and off Retin-A for ten years, I still struggle (and especially now, for hormonal reasons). I am scarring and dealing with hyperpigmentation and I blame Aldactone and hormones, but I have researched this topic a lot.
I can't tell you what's helped me because my skin (to quote a dermatologist) is "one of the toughest cases of acne she'd ever seen", but I can tell you where to start if you want to look more into certain methods. You might do better than me.
The one (aloe based, cheap, drugstore) product I've used that hasn't broken me out and can be worn under make-up is Triderma Facial Redness Moisturizer. If I could afford it I would also buy more stuff from Derma E (one brand to look into for their skin-clearing stuff).
Wear a sunscreen (Olay Complete SPF worked for me, Neutrogena Clearskin is now being sold for acne-prone users in stores, but I can't review it; if you can tolerate something like Coppertone Sensitive for Faces SPF 50 of a physical sunscreen, do it.) Trader Joe's now sells their own SPF 15 moisturizer, which I might try. Sunscreen keeps dark marks from darkening.
Skinmedica and Skinceuticals also sell physical sunblockers.
Go to skinstore.com, drugstore.com, sephora.com, iherb.com (natural products), Amazon, ebay, Paula's Choice, Jan Marini, Skinmedica, Skinceuticals, Mario Badescu, Neostrata, PCA Skin, Nia 24, etc. online or any beauty supply online outlet and look for a "tone correcting" or "dark spot/pigment corrector" product. Neutrogena sells a "tone correcting" serum. Be wary of anything with comedogenic ingredients in it if you are still prone to breakouts. http://beautifulwithbrains.com/2009/06/10/what-ingredients-are-comedogenic/
Unfortunately there is hardly any skincare product or makeup item I've found--even benzoyl peroxide gels, sometimes--that doesn't have a comedogenic ingredient in the list somewhere. Just try your best.
Now, for the list of things supposed to help with dark marks (your mileage may vary, but at least you can research these):
1) Vitamin C (anything from basic lemon juice to drugstore stuff--Proactive makes a dark mark corrector, L'oreal, Garnier, Avalon C Organics, Dermalogica Chromawhite, etc.).
2) Niacin (Olay--meh; also in Nia 24 products)
3) Mandelic acid (I've never tried it) from MM2
4) Exfoliants like glycolic acid (BHA? AHA? Look it up), lactic acid, azeliac acid, or retinoids (Tazorac, Retin-A). Unfortunately these no longer work for me. Glycolic breaks me out, but some people love it it. (Note: you can find these in washes, serums, treatments. Neutrogena Fight and Fade uses glycolic acid, but as noted, it broke me out.) You can also try these in chemical peels.
(MakeUpArtists'sChoice online gives cheap samples.)
5) Copper peptide. (Sorry--not sure what to recommend here, other than Neostrata. I know Owndoc sells some. Sarah Vaughter's name is banded about here and she says brands like Skinbiology are phony.)
6) Bleaching agents like hydroquoinone--A bleaching agent sold in drugstore creams like Nadinola, Porcelana, Ambiskin, or Black Opal. It can also be prescribed. I haven't tried it and am scared to. Research it first. But some people wear by it. I think Black Opal honestly sells the least comedogene-filled products. They also sell a dark spot corrector for "sensitive skin" without it; instead, it contains Sepiwhite
6) Dermaneedling for actual scars. (Dr. Roller sells decent rollers; I bought a kit from Owndoc.com and am waffling whether I want to try it because my skin bruises/forms scars so easily, but again, I consider myself a special case.)
7) "Natural" stuff with vitamin C or E in it--when I was on Accutane and every mildly oily product didn't break me out, Biafine (ask for a prescription or look on Ebay) was the one thing that helped with picked pimples and marks (but my skin was far more resilient then--still). The key ingredient was avocado oil. I've never tried that by itself, however, but you can buy it to cook on Amazon and in American drugstores it's sold by De La Cruz.
After that I'd recommend you search these boards for info on treatments (including natural oils, dermastamping, and dermaneedling scars).
I'm sorry I can't give actual reviews, because admittedly I've been inconsistent if something breaks me out, causes irritation (and thus, more dark marks), or tears my skin, which has difficulty healing. I bought Skinceuticals kojic acid (it's green and the damn tint stays on your skin even after the runny serum absorbs; not getting many benefits from it). I tried vitamin C powder from Owndoc and it seemed to help some, but I'm breaking out now so I don't want to put anything that made me sore--which it did--on my face.
Persagel or the CVS knockoff is the only thing that helps with cysts, but benzoyl peroxide makes skin darker. I think Oxy makes a less severe 5% BP ointment that some of you might look into. When I was on Accutane I could put 1% hydrocortisone cream on cysts to flatten them (but it also made the skin thin and pink)--that no longer works for me, but it might for you. Walgreens Cortizone gel with aloe is one ointment that doesn't have isopropyl myristate in it.
If you're outside the U.S. you could look for these ingredients in Boots products.
Honestly some of my pitted marks/wounds healed with time but it took bandages (I know--how silly) and Bactracin (not Neosporin--Neomyocin, one of the ingredients, is supposedly a sensitizing agent, but don't quote me on that.)