AHA are best used from several times a week (2-3) to using daily as a treatment or when using it for the first time. Extended application is important for results, but so is a rest period if you are using them daily all year round. The AHAs are fruit acids, and work by dislodging the superficial layer of the skin and encouraging a more rapid cell turnover.   Usage for the younger person or more sensitive/reactive skins should be every other night for six months followed by a month without treatment, all year through. Frequency, and sometimes strength, are increased for older people and those with more damaged skin, who need the treatment more, in this case use product daily for 3-6 months then cut back usage to  2-3 days out of the week all year through and alternate with another cream OR serum. Or you may wish to do a treatment twice yearly (after the winter and after the summer) where you use product daily until it runs out ..... Continual daily usage has been very well tolerated among some of my clients, with a a rest period. If you do use aha products during the summer months you need to wear a cream with spf during the day...... It is not recommended to use a serum under aha creams! use your serums with your day cream when using aha...  or use serums when you are not using aha..... some clients do use a serum along with their aha cream with no problems and great results., do what is right for your skin. If you use aha daily or 2-3 times weekly then you do not need to exfoliate once weekly..... but I do have clients who do still exfoliate using caution and  do so once or twice a month to every other month or as needed...... Use more often at first to remove the buildup of accumulated dead cells and then to maintain cut back it's usage to what works for your skin. I recommend to use aha's once daily at night. You can apply your favorite cream over it if you wish if  you feel you need   extra moisture.....I recommend when you start using AHA for the first week to use every other night and work up to daily the second week....For more sensitive skins you may also dilute this cream by adding half of dose to your favorite cream then apply to face... AHA WILL MAKE YOUR SKIN FEEL firmer, LOOK brighter, HELP stimulate collagen production, EXFOLIATE, HYDRATE, REDUCE the look of fine lines and wrinkles, SEAL in moisture  AND so much more! Remember repair of damaged skin takes time! People over 70 years old should not use aha daily! For some skins you may experience a sensation of warmth and a light tingling and/or the skin may show signs of sweating this is all quite normal and excessive skin flaking/peeling for the first little while may be experienced by some - this is normal too.....