I would think that depends on what you want out of your dancing.
If you want to compete, others have given you pretty good advise.
However, if you want to have fun and friendship, you might look for a person who is fun and friendly.
There are many reasons for wanting to dance. (Physical exercise, fellowship, mental exercise, desire to compete with others, and lots more.
Some folks are even looking for someone to spend the rest of their life with.
You have to decide what you want out of your life. Only then could anyone tell you what kind of things to look for in a dancd partner.
Michael