First rule: write something short and memorable, even if it's not as detailed as you want it to be.
Second rule: do not describe the appearance objectively, but subjectively - focus on impressions and emotions.
I always try to do both of these things, and it's important because no one is going to remember a number of details about a character that was described twenty chapters back. I could write three paragraphs about someone's body shape because I imagined how they would look like exactly, but no reader is going to apprieciate something like that unless it's a situation that calls for it (for example a detailed examination of a corpse or describing a detail, such as a mark, important to the story).
I personally do three things. Keep in mind that's my own method that might not work for everyone.
1. General impression, for example "a scrawny boy" or "an exotic beauty that caught his eye". This is the simplest part, but arguably the most important, since the impression is what people pay attention to the most. Say a blonde bimbo and everyone will remember who the blonde bimbo is next time she's mentioned. Say someone has blue eyes, and most people will forget it unless you remind them.
2. Noticeable details. This can be literally anything, but generally you have a couple of things that are most noticeable in a character. What it is exactly would depend on who it is, because you obviously won't write a man had narrow hips cause it would sound weird. Try to choose two or three things and don't describe anything else, only skim over it.
3. Feelings, impressions, and thoughts (not necessarily said directly, can be implied), which can be inserted alongside the two other, for example "hair that looked like it hadn't been washed in too long" or "her short stature highlighted the ridiculous size of her sword".
A lot of it also applies to different things apart from appearance, for example clothing.
Also as a random tip, try not to describe what can't be seen or known when you describe the appearance. When you're not doing omniscient pov, you can write "his hands, covered in callouses, made her think he did a lot of physical work" but try not to do something like "his hands, covered in callouses from physical labor, ...". Unless there's a good reason to, such as redescribing character appearance after some event.
The difference is subtle and some may say unimportant, but it helps to set a specific perspective and keep to it.
And to apply all of this to describing a beautiful character.
First, impression, what kind of beauty it is. It can be cute, hot, otherworldly. Every beauty has some kind of type, even if it's androgynous. That can be said directly, but doesn't have to.
Details, so what's most noticeable. Golden hair cascaded down her back, seemingly sparkling as she approached. Her expression turned impassive and her face tightened, only ephasizing its sharp lines and not betraying any emotions. They stared at her, at the generous bossom held tightly in a revealing light green dress and at the dark skin underneath, black like smoke and ethereal. It was the eyes, however, that stopped theirs - narrow, deep green like gemstones, and strinkingly bright in the dim lighting.
See that the third point is already there, within the second. The first is there as well, although it's only implied.
