Women are, by far, attracted to and affected by the words a man says more than anything else. That is not to say you can get away without showering, but you should focus energy on developing your speechcraft before you waste time obsessing over your height. I have spent many hours reading and writing in order to develop a clarity of diction and thought that I use when I am doing pickup. It helps to have a quick verbal mind when you are talking to a stranger. It helps reduce awkward silences because you will likely have some thought to share.
By spending time alone writing blogs (like this one) and reading for my own sake I am able to be more witty and quick with girls when I talk to them. Writing especially is by far the best exercise for becoming more seductive. As I write each post on this website I cement these pickup concepts deep into my long-term memory. Not only are the pickup concepts true but the very act of writing these entries gives me exact phrasing for each of my opinions surrounding women.
Exercise is also helpful indirectly. I would not say that running/walking helps you talk better but it does help you release negative and difficult emotions before you talk to someone. So, I count exercise towards speechcraft. Reading is of course the final frontier here. I recommend that you read fiction books that involve lots of conversations. They can be sci-fi or fantasy or whatever. Books are like simulations for your brain. You don’t have to read romance books unless you like those. You just need to get those word muscles flowing.
Pronunciation and accent may also play a role. In America, I have noticed that it isn’t the foreign men who speak perfect English who get the girls. You can get away with having a pretty heavy accent and still date an American girl. There is however a certain minimum level of intelligibility in your accent that needs to be present to talk to an American girl. By the way, I used to live in Europe in a non-English country so I’m not being an asshole here because I used to get rejected for my poor language skills in that country.
Spend time with your friends. The more you talk with your friends the more confident you become in general so keep going out with your buddies and shooting the shit. Of course you might talk a bit different to your girlfriend but you will still have to talk to her!