Great question and my answer is a simple one: You already have a partner, your husband. Business partnerships more often than not end up in a disagreement and almost always mean one partner buys out the other. I would seriously question any need to have a partner when someone could easily be employed for a fixed wage.
But if you insist on bringing on a partner, then take these things into account:
1. Know the person well and hopefully work with them first for a period of time. Only one partner can work in the business, or if more than one, make sure it's clear which one is the boss. Write a Separation agreement, for when you break up, not if.
2. I would also include a buy-out clause in your partnership agreement that clearly states what the buyout agreement will be. I like a reciprocal clause, where any offer to buy or sell is also an offer to buy or sell the other partner at the same price. Ask your lawyer if you need this better explained.
All the best,