But I would suggest paying attention to the houtengeki art book, he clocked the milf aesthetic even if he mostly makes young girls.
I image searched for his name but it was all 12yo cat girls with big tits & ass. the only thing he seemed to do was give them the bigger asses and tits, which is like the first thing you do for milfs. didn't see any actual milfs but maybe I just didn't get the right hits.
I find that besides making them voluptuous, a tiny amount of preggers belly adds to that 'after first child' body change from a tight teen body. also giving more softness/roundness under the jaw while also sinking cheeks in slightly works. thin lips are always technically correct but I tend to avoid that to keep the milfs looking more juicy.
a lot of what I do is a compromise between biologically correct and hotness, because at least for me there's no point in making a realistic 40-50yo character that's not hot anymore. I'm well aware those less hot milfs have their own audience, but it's just not for me.
IF I could get fine enough wrinkling I'd use it around eyes, but usually they're just way too large which makes the character look like 70-80yo. I've thought about making a wrinkle map and baking that into a normal map but even there the issue probably becomes not having enough resolution unless you use gigantic skin textures. I guess you could make some kind of a geograft around eyes to add resolution only there, but it all seems like way too much work just to add a slight nuance almost no one will probably notice.
it always comes back to it only working well if you render everything in blender, but it's a giant hassle and still the translucency will probably look kinda flat.