First of all you need to be a good partner to yourself. Yes, you need to be content with where you stand in life. You need to at least know your plans and goals. Don’t be a pushover and lost. If you don’t have it figured which, most of us have not… try to plan and know what you want.
Many people who are always lost and lack initiative would tell you, yes but, everyone is lost, you just don’t know what will come your way next. That is true, but at the same time, you need to know what you like and don’t and stay true to your values.
Right off the bat, good money sense! You don’t want someone who doesn’t know what they are doing with their money. You don’t want someone drowning in debt, you don’t want someone who is not saving! Also, you don’t want someone who doesn’t have a retirement fund.
Trust/Understanding. You need to find a best frined in the partner. They need to understand your drive and purpose. Again going back to my first point, you have to have drive and purpose. You have to keep on working on yourself. Growth is the key to life.
Understanding comes from open communication. Don’t be afraid to have deep conversation so you both can learn more about each other on an intellectual and emotional level. This will allow both of you to keep yourself honest.
I feel those are the core for a good partner. Obviously, there are more things to add per your own personal preference.