From my experience the more you work on scars when they are fresh the quicker and easier they go away. I am olive skinned so I scar very easily and I found a websie called perfectcomplexion.net where they sell salicylic acid at 18%. I use this on newly formed pimples to make them go away quicker and keep them 'fresh'...the skin over the pimple dries up and peels off and then the skin under stays pinkish(fresh). Then once the pimple is popped and the spot is starting to heal I use the microdermabrasion crystals that she sells with vitamin E as a carrier. That stuff is pretty awesome. I feel like I have a new face and it makes my scars noticeably lighter in one treatment.
She also has a TCA peel which I use as well every few weeks.
The only thing about the crystals is I don't think its good to use them on new pimples or sores. I haven't been able to use them in about two weeks because I brok out really bad. Hope that helps.