If you can stand the heat, steaming with water is simple, free, and very effective. It can be a precursor to most other facial treatments, although salons will use steaming machines rather than have you hovering over a steaming pot.
You can add herbs or essential oils to the hot water before draping a towel over your head and hovering above the pot for as many minutes as you can stand. I’ve even tried mixing Noxema with cornmeal then exfoliating after steaming to get rid of loosened skin cells (that just sound so attractive doesn’t it)!
In terms of scientific safety, it depends on how you define “safe”. Facials that promise to smooth your skin have exfoliants (these can be synthetic, which would be “milder” because the synthetic exfoliating beads would be round, versus apricot kernels, which when broken could have micro edges that can be too much for sensitive skin) that are abrasive however mild.
Even chemical peels can make your skin raw if the chemical (usually an acid of some sort such as glycolic acid or salicylic acid) content is too high and your skin is very sensitive. Even those enzyme peels act by “chewing” the bonds holding skin together, chemically sloughing skin. For some, chemical peels can be problematic because it can burn your skin, make you more sensitive to the sun, and otherwise cause an allergic or adverse reaction. Start with a lower percentage for example 5% glycolic rather than jumping into 10% or even 12% if you want to go the chemical route.
Then there’s physical peel-type of masks, which literally glues onto your skin and “lifts” off whatever blackheads or cysts or skin debris that is stuck on the glue.”
The way that these facial treatments “improve” complexion is by sloughing off dead cells so that your new skin cells and grow and come to the surface. So actually it’s your own skin that is doing the “improving”, the facial acts primarily to remove old and dead cells so that your younger new skin cells become visible on the surface.
P.S. All the above were “knowledge” from my younger years when I had lots of time to mess around with my face and try different things. Now as a mom I consider myself “pampered” if I washed my face with whatever soap’s handy and slap on moisturizer with sunscreen.