If you decide to go with a partner, make sure your job descriptions are laid out in writing before hand. Every aspect of running the business should be assigned to either you or your partner. You have your responsibilities and your partner has his. You don’t interfere with his job and he doesn’t interfere with yours. For example, if your partner is responsible for advertising, you can offer advice but he has the final say and vise versa. If this is set in stone from the beginning and you both agree to it, it will save a lot of arguments and disagreements in the future that could ultimately break up your partnership.
You should also sit down with a lawyer and go over every possible thing that could go wrong with your partnership and how it will be dealt with. Include all of this in a contract. Also plan a detailed exit strategy (buyout option) for both your partner and you.
These are only a few things that I recommend. If I were you I would do some more research on partnerships. A lot of information can be found on the internet. Also do a search of this Think Tank. If I remember right, there was a great post on here about partnerships a few years ago. I don’t know how far the pmq Think Tank archives go back but it would be worth looking for. It was written by lady (she might have been a lawyer) who had legal experience with partnerships. She went over every aspect of what should be included in a partnership contract. She also went into the pros and cons. It was very informative.