Professional dancer here. I love dance and I think it does great things for people that get into it, beyond dance itself.
The prospect of girls got me interested, but I fell in love with dance itself shortly afterwards.
Youtube is the best way to introduce people to good dancing. Contemporary - check out Sidi Larbi, Akram Khan, Batsheva, Bryan Arias. Popping - Salah. Breakin - BOTY, Lilou. Competition Latin - Slavik Kryklyvyy
Anything that strengthens the muscles that control the pelvis and spine will be a great exercise. Standard positions will vary depending on the style of dance.
The real question I want to answer is how to become a better dancer. The most useful answer for a beginner is to have a lot of fun and not to worry about what anyone thinks. A certain blindness to your deficiencies will help the love of dance grow and you will need that when things get tough.
The real answer, in my opinion, is to stop seeing dance as dance. It's a mode of communication. The sooner you realize that, the less concerned you'll be about style, positions, shapes, "coolness", technical prowess, etc. Like music, it's not just hitting the notes (body positions & shapes), but how you fill those notes out with warmth, coldness, power, softness, etc. - to communicate the exact mood you'd like to convey to the audience.
Notice that great dancers speak. They choose their words (movements), enunciate clearly (clean enough to be seen and processed by audience), and pace the speech in a way to hold the audience's attention (alternating fast/slow, high/low, big/small) in the way an orator will vary her rhythm, volume, pauses, etc. Great dancers look more like they are just living life vs. performing.
No matter what style of dance - classical Indian, commercial hip hop, ballet, breaking - the best practitioners show that they are just different modes of speech, different "accents" and moods. The more moods and accents you can acquire, the more accurately you can communicate and the more powerfully you can move someone.
Continuing with the speech analogy, just because you have passionate feeling doesn't mean that you can stir an audience into a frenzy. You have to know the language (standard steps and positions), be able to project your voice (balance, power, flexibility), you have to be able to hear yourself speak so you know whether you sound like an idiot or not (being able to see/feel dance differently). So, basic training is super important - but it's just a means to an end. Don't get caught in the trap of trying to be a perfect technician. You'll never get there, there will always be someone better, and it's easy to become a snooty asshole. Really? You're a more worthwhile person because you can get your leg higher than the person next to you? Please.
Wow - rambling a bunch, but I hope you get the conceptual place I'm coming from. Concrete advice below:
1) Learn to see differently. Watch others. Dissect the movement. Watch yourself on video (a lot - video makes you look bad, so if you look good on video...). Are the shapes just shapes or is there an energetic projection, if so, how far? Pay special attention to the pelvis and spine, especially when flashy arm, leg, and head movements are happening. You'll see pelvis/spine support everything.
2) Learn to feel movement differently. Two ways to move. Use your own muscular tension, or imagine the space moving you. Generally you want to use the second, you'll be faster, more precise, more powerful and save energy. Example - I want to lift my arm. Option 1 - Use my muscles and get to the position. Option 2 - Imagine there is a deflated beach ball under your armpit. The beach ball inflates and that is what moves your arm. Option 2 is almost always better as you can control the speed, and range of the inflation with the minimum amount of muscular tension. Using Option 1 generally results in stiff, dead, fake, imprecise movement.
3) Pelvis/Spine is everything - no matter the form - ballet, modern, hiphop, salsa. Imagine the pelvis/spine as a 3d paintbrush, be ultra aware of the position, twist, level, angle, and rotation of that chain as you "paint" (move around) the space with it. In any high-level dancing, every movement of the extremities - arms, legs, fingers, toes, head, eyebrows starts in the pelvis and spine (and by extension the abdominal muscles that control them). Tune into that connection (sometimes it's very subtle) so it becomes clear and every movement you make will have power, presence, and value. Once you get this you'll see all dance styles are the same. All the best dancers from any form are moving from the pelvis/spine, are aware of what these things are doing in space. Extremities are secondary.
4) It's just dance. It's not that serious. (But neither is life).
Good luck and best wishes!