1. Hobbies
If they do not have any hobbies of their own, chances are pretty probable in the long run they are not going to want you to have any either. Make sure your level of happiness matches, that includes hobbies and being around other people. Do not let anyone tell you that you are not allowed to do something that you really enjoy. If your potential partner is weird about you playing your favorite sports on a league with your dudes, or if they are weary about you joining a new yoga class or going to the gym... BYE BYE!
2. Dedication
Observe how dedicated they are in all aspects of life. Look for someone who wants to achieve the best and are dedicated to not only you, but themselves as well. Someone who is not motivated may bring you down a dark path and could make your life extremely depressing.
3. Family
Watch how they speak to your family, their family, and their friends family. It means a lot having respect and being presentable. There should never be a time where your partner questions your family either. If they do - or try and take time away, that is a huge red flag. A big no no.
4. Trust
Once you guys get over the lovey stuff and start figuring our each others corks be sure to trust them. I know you are SOO IN LOVEEEE. That does not mean look through phones, go through rooms, and stalking each others social media. It means let each other live the lives you love, figure it out together, and trust one another. If you care - you know that person would never do anything to hurt you. If they do, and destroy that trust - call it quits. There is no room for mistrust in a relationship. It will destroy you.
5. Friendship
Friendship is so important! As in - make sure the person has at least ONE best friend. If you find someone who does not have friends - chances are pretty probably you will be getting a crazy person as a partner. Look at their friends and get to know them, it will say a lot about that person. ALSO, establishing a friendship between you and your potential partner is critical. Take it slow, make sure you can be yourself around them. Don't start out some lovey dovey person and turn into one of those narcissists who reel you in the first month then start calling names and getting possessive. If your potential partner is talking smack about their only friend as well - ICKYYYY BYEEEEEEEE. NO WAY.