Modern words to compliment a beautiful woman/girl beauty
美女 is the safest choice. 

宝贝 is used to call someone (boy or girl) who's in a romantic relationship with you, or you call a baby girl (usually aged &lt; 10) 宝贝.

女神 nowadays has some negative meanings and is not recommended.

Other similar choices are 小美女，靓妹.

An example in wechat: