There was a time when the thought of platonic friends of opposite genders living together was thought absurd, however times have changed. It isn't unusual at all for co-ed roommates to share an apartment, but this living arrangement comes with its own unique challenges. Global Post.com has tips for what you should think about before signing a lease with a buddy of the opposite sex.
Psychologists have found a phenomenon called the "revelation of possibility" that occurs when friends of opposite genders are in close proximity with one another. Often friends in this situation will become attracted to one another. This doesn't mean that it's a foregone conclusion that you will become romantically involved, or that you even want to, but it is important to be aware of this effect and try to avoid it. Be conscious of flirty or intimate touches between you and your roommate. A good rule of thumb is if you wouldn't feel comfortable exhibiting the behavior in public or in front of a romantic partner, it's dangerous.
If either of you are in a relationship, your significant other(s) may not be so excited about the prospect of their romantic partners living together. Have a meeting with all parties to make sure that your boyfriend/girlfriend knows there won't be any roommate hanky panky. Also, set rules for how often each of you can bring home dates.
Make rules for modesty. You may think it's totally fine to wander around the apartment in your undies, but your roommate may feel differently. Set expectations now so no one is offended later.