Dress well
Here is kind of a no-brainer but you would be shocked as to how many people just do not think about this at all. By dressing nicely and putting some effort into your wardrobe and overall presentation, people will look at you differently. They may show you more respect because you seem as if you respect yourself.
You look more approachable if you are dressed nicely, more professional, and trustworthy. These are all things that you will want to have if you are planning on expanding your social circle and making new connections, possibly romantic relationships as well. Remember, you do not have to be a style icon but just know the basics.