Hi bringit! Welcome!
You didn't really mention why you think you need a partner, or was it just that you thought it would be 'easier' to operate a business with one? That wasn't clear. Also, you don't talk about the investment because one thing that I will tell you for sure... is that money changes people. It changes them in a lot of different ways.
I speak from being both a sole operator and a partner. It was told to me at one time that partnerships were created ONLY to have one sole owner (eventually).
First of all, if it's money that you are looking for help with, there are a lot of different ways of getting money without making the person a partner.
On the other hand, if it's because you really think you need a partner, then the only thing I can tell you is that no matter who you pick (family or otherwise), yes, I said it... FAMILY or OTHERWISE... be sure you have a partnership agreement and that you DO NOT both use the same lawyer.
Partnership agreements are great because they provide a clear and easy way to break the partnership should one person want out. I say they are great because you are talking about those possible 'bad times' while everyone is still talking.
I don't suggest each use their own lawyer because I like lawyers... but only because you don't want YOUR lawyer not discussing some parts of the agreement (or anything like that) where the other person could be compromised. After all, depending on who brings the lawyer, that 'other person' could be you. Just get your own lawyer, ok?!?
The only other advice I can give you is that surer than God made little apples, you will come to a time when you don't see eye to eye with your partner. Whatever you do... no matter who you pick... no matter how much you like or agree with that person... be prepared for the break.
If that other person disagrees with your choice to have the agreement in place now, then don't walk away from that potential partner... run!
Hope this helps!