For me, the most important thing is looking closely at my skin and determining what it needs that day or week.
Every morning is a splash of cool water to cleanse or if I see a residue of moisturizer from the night before, a mild non-sudsing cleanser. Foamy/suds can mean sulfates which are drying to skin just like it is to hair. I then procede to Vit. C serum, a lightweight moisturizer and my spf which has moisturizer in it. Then a rich eye cream. That's it for morning. I may exfoliate w/ an acid pad if I see any rough patches.
At night, I double cleanse with an oil cleanser (face and eyes) and then a gentle one (same as morning) to be sure all makeup and spf is removed. Then every other night is Retin A prescription .1% that I started at the lowest dose at least 35 yrs. ago. The other nights, in winter, I apply a heavier moisturizer and sometimes seal it in with an oil...marula or jojoba.
Each season, I do an at home acid peel and 3 times a year, I do the OBAGI SYSTEM that has 4% hydorquinone (have to get from my derm) to fade darker spots and exfoliate. The system includes cleansers, exfoliates, the hydroquinone, spf and a Retin A. The products are numbered andl ined up on my counter. That will be all I use for the 6 weeks instead of my usual skincare.
I do have several moisturizers to be able assess what my skin needs. On makeup days, a lighter one (Bobbi Brown Vit. Enriched) which is also a primer. I have heavier ones or balm textures when skin is very dry. In the summer when skin's not as dry, lighter moisturizer is good for my skin and I use my Retin A more often at night.
I do stay with products I like and do not switch or purchase new ones very often. If it isn't broke, why fix it? Many women have an arsenal of skincare products and never give each of them long enough to see results...sometimes 3-6 months is necessary to judge. Retin A can take a year.