Phenethylamine is a chemical that, in our brains, is interpreted as euphoria.

It's a runner's high, the thrill of riding a roller coaster or falling in love. It's also released when we eat chocolate, sending out opium-like endorphins that make us desirous for more of the same sensation.

While we'd like to consider ourselves logical creatures, we're still animals who rationalize the choices that our bodies have already made. Almost nowhere is that truer than in our romantic lives.

Your sexual compatibility with someone is spelled out almost instantly. Chromosomes, as expressed through the pheromones we emit in our sweat and perceived through sense of smell, are way more important for arousal and attraction than the game we spit. And the likelihood of long-term success hinges heavily on the earliest phases of a relationship and the initial physical reactions we have to each other.

That's not to say, however, that you can't affect the outcome. Knowing how our bodies and brains react to various stimuli, we can cultivate a first-date experience to maximize your crush's interest and investment.

Brains are amazing, but recognizing the source of feelings is not necessarily their wheelhouse. Almost every article on first dates points to a study from the 1970s that finds being physiologically aroused while in someone's presences makes us more likely to be attracted to them.

The idea is that when I feel my heart racing and adrenaline pumping, I associate it with the person with whom I am riding the roller coaster, not just the ride itself. Technically, the hottie I see after I get off the Tilt-O-Whirl is going to seem more arousing than the one I saw while waiting in line because, in my dumb brain, my heart has been racing every time I've seen them. But in any event, it's wise to do something that gets your heart going, like hiking or rock climbing. Horror movies are good, but because there's minimal chance to interact, it's not ideal for early dates. At bare minimum, have coffee so that you get the effects of caffeine.

It's thoughtful to pick a spot that's convenient for your crush, but, unfortunately, that will cause an unconscious devaluation of the prize of getting to see you. Again: We justify the choices we've already made so we can retain the idea that we're logical. The more effort we have invested in something, the more we convince ourselves that we really wanted it. By having boo jump through a minimal hoop to get together, it provides evidence (to both of you) they are into you.

There are also small details to consider. A dark room causes the eyes to dilate, which also happens when you're attracted to someone. We look at our romantic partner's eyes more than at others, and researchers suggest it's because we're unconsciously examining their pupils for signs of arousal. We are turned on by the perception that they're turned on, even if it only LOOKS like they are. Also consider the mood set by the décor and music of the venue, because (again), we associate our reaction to a situation with the person who is there.

Intimacy is built exactly one-way: mutual vulnerability.

When you share stories from your embarrassing middle school years, you reveal that nonsensical phobia you have. We have dirt on each other now, building trust and closeness. But according to Social Penetration Theory, this has to be a drawn-out process and literally cannot be rushed. A lot of early self-disclosure won't necessarily lead to greater intimacy. In fact, too much can have a repellent effect.

The subject of your previous relationships is forbidden for at least one date. It almost never is necessary, creates the appearance of being stuck in the past, and will shape the way you both approach the new relationship. Get away from anything that either tries to re-create or contrast dynamics you had with an ex and focus on writing an entirely new narrative with this current object of interest.

There are entire courses just on the physical aspects of flirting: stance, proximity, eye contact, mirroring postures, and reading when it's a good idea to go in for a kiss. But it's outside the scope of this and likely far less relevant to your success as a well-planned strategy for when to start getting frisky.

Putting in some small touch early on is necessary to cement that your interest is more than platonic, but early physical aggressiveness is rarely good for long term success. Even among the most sex positive and feminist, a first night hook up can diminish the odds of a substantive relationship for the same reasons that talking too much about your problems with your mother might. We can only acclimate so quickly. There's no moral imperative to wait and plenty of exceptions, but there's a reason the Three Date rule is so commonly applied. Specifically, people with either very little or a whole lot of sexual experience find greater long-term success with a partner when they hold off on tearing it up.

Most importantly: Be you.

Be the best version of you, but be the real you. Authenticity, confident vulnerability and enthusiasm are universally attractive.

Dr. Timaree Schmit earned her Ph.D. in Human Sexuality from Widener University, where she now trains future sexologists and clinicians. Her passion is bringing rational, empirically-based, sex-positive information to the world, empowering others to celebrate their bodies, build intimacy and experience pleasure. 

She has an award-winning podcast, "Sex with Timaree", and hosts a BYOB sex ed, comedy/game show "DTF: Darryl and Timaree Fun Hour" which can be seen every second Friday at the Philly Improv Theater (2030 Sansom St.)