The basics would be:
Personality – introverted vs extroverted
Hashkafa/frumkeit – tznius, TV/movies, secular music, internet etc
Family’s hashkafa/background
School/work/stay at home mother
Age
Intelligence
Height
Specific middos you value
What you do not want
Eretz yisroel (if you want to live there)
Looks
OOT or not
Ashkenaz/Sefardi/Chassidish/Litvish
BT/MO/FFB
What you will not compromise on
This is just a list. Be flexible and willing to compromise 🙂