In order for two parties to decide to go into business together, they often have to share similar goals, approaches to doing things and similar outlooks for the future. Oftentimes when they fail, it's because they no longer can see eye-to-eye on these same issues. This is why, before you go all in, share resources and get your finances entangled, there are a few steps that you and your business partner should take to protect yourselves.
First, you'll want to make sure that you and your prospective partner don't engage in any substantial business without having a properly executed operating agreement in existence between the two of you. You shouldn't plan to make any significant life changes such as purchasing an office, moving to a new city or entering into any financial agreements without it.