The sign for "woman" has a couple of variations.

Here is a good general version used by many adult, native Deaf. Touch the thumb-tip of your dominant "5"-hand to your chin and then bring it down to your chest.

WOMAN:

Notes:
Regarding this version: Students sometimes ask me, "Isn't that the sign for mom?  My other instructor showed me a sign that combined the signs GIRL and FINE."

Response:  The sign "WOMAN" has evolved over time to the point where the initial handshape and movement for the sign "GIRL" tend to be dropped and the sign actually looks more like a combination of the signs "MOM" and "FINE."

MOM + FINE  = "WOMAN"


However, I really don't think that the first part of the current sign for WOMAN is actually based on the sign "MOM" though.  I think that the dominant hand (your brain actually) is simply anticipating the final handshape and for efficiency sake the first handshape (GIRL) has faded out (been dropped) over time.
 

But yes, I still see people doing the GIRL + FINE version of WOMAN and it is an "OK" sign.
To help you remember the sign think of it like this: A woman is also sometimes called "a lady." A "lady" is a "girl or female who is refined" or a "girl who is fine." So a combination of the signs "GIRL" and "FINE" end up representing the concept of "WOMAN" (or lady).

WOMAN: FEMALE + FINE (version)


 

Regardless, you should do your signs however your local (qualified) teacher or local (skilled/native) Deaf do them.
 

See: LADY