Formal:
* À quoi ressemble-t-on? (What does one look like?)
* Quelle est mon apparence? (What is my appearance?)
Informal:
* Comment je suis? (How am I?)
* À quoi je ressemble? (What do I look like?)
* Je suis comment? (What am I like?)
To describe your appearance in French, you would then follow one of these phrases with a description of your physical features, such as:
* Je suis grand(e) et mince. (I am tall and thin.)
* J'ai les cheveux bruns et les yeux bleus. (I have brown hair and blue eyes.)
* Je porte des lunettes. (I wear glasses.)
* Je suis de peau mate. (I have olive skin.)
For example:
* À quoi je ressemble? Je suis petite et corpulente, j'ai les cheveux blonds et les yeux verts. (What do I look like? I am short and stocky, I have blonde hair and green eyes.)
Remember to adjust the formality and the level of detail based on the context and your relationship with the person you are talking to.