That's a difficult question Ant. You'll get a different answer from most everyone.
For me, open, honest communication is a must. You gotta listen with your head, and fall in like before you fall in love.
Falling in like makes marriages last 50 years.
Falling in lust makes alimony and child support payments that last pretty long too.
Overly attractive women have never tickled my fancy. I like fun girls with an easy laugh that like to fall asleep watching old movies with their head on my shoulder.
(then I can get back to work!)