Don’t rush into a partnership.
It was only after my original partner and I parted ways that I recognized that we should never have had a professional partnership in the first place. Just because someone is your best friend, long-time coworker and / or significant other hardly qualifies that person as the perfect candidate for maintaining a business. I say “maintaining” because it’s far easier to get excited about the prospect of starting a company than being able to handle the day-to-day reality of running it efficiently.
The best partner is typically someone whose skills and approach are the polar opposite of yours. The first ensures that you are able to cover a lot more ground without additional employees. The second may create conflict, but it will force you both to defend your business instincts and weed out lesser ideas before you waste resources.