As far as I know you can't use acids over retin-a. It reacts with the molecule making it ineffective (or maybe just less effective. I'm sure you can you the cetaphil moisturiser over it though, and you might need it. I've been on retin-a for 2 weeks now and so far it's just dried my skin.

I think you have to be very careful using Retin A with other active products. It can be very tough on the skin just on its own. My sons used it for a year, on its own, and I honestly don't think it helped at all. Their skin is fair like yours and the Retin A just seemed to make their skin red all the time and never really prevented new pimples. I also never saw any dramatic clearing of the red marks that some people say it is good for. There were always new pimples forming so that just led to more red marks and it was a never-ending cycle. It also thins the upper layers of the skin over time and I honestly thought the texture of their skin worsened and their pores were more visible the longer they were on it.