One thing I've found that is important to address early on is expectations about time and arrangements and make sure everyone is on the same page.
My very limited experience has been that non-poly people have no framework for how a non-monogamous relationship functions on a practical level so they either fall back to assuming things will look similar to a mono relationship or they have fears of the unknown and are hesitant to move forward.
If you haven't already talked to your husband about this it would be a good idea to address how often you might see this other person. Once or twice a week? Every day? All day on a weekend? What about sleepovers? How soon would you like your husband and potential partner to meet and what are they comfortable with? Do you anticipate being able to spend time as a threesome or would it be mostly separate? Are you out to your friends and family or do you need to keep this relationship private? How do you feel about displays of affection in front of each other? What about in public? How much do you share about one when talking to the other?
Once you and your husband are in agreement, you have something concrete to offer your potential partner in terms of time, attention, affection and privacy. It's helpful for the new non-poly person to see that you've thought this out and has a good idea of what to expect and that your husband is in agreement and accepting of the relationship. Good luck!