First, best, and easiest thing you can do to improve your portrait work is to shoot an interesting subject. They don’t necessarily have to be a professional model, or even conventionally ‘beautiful’, so long as the person is fascinating to YOU. Start with that before you think you need to upgrade any gear.
Secondly, a good basic, no-cost set-up is to side-light your subject using natural window light: position your subject perpendicular to a large window, about 3-5 feet away; open up your apertaure to 2.0; be careful to put your AF square on their eye and do NOT recompose, as super shallow DOF is not very forgiving with movement after focus-lock.
The last thing you should try to do is elicit some kind of emotion from your subject— this is where you as a director will come into play, which trumps about any other aspect of being a photographer… more than lighting knowledge, technical prowess, or expensive lenses&bodies.
…as you grow as a photographer, you can always hire assistants&crew to light complicated schematics, retouch your images, or create compositions/sets… but when it comes down to it, it’s your sole and unique ability to draw a performance, look, or emotion out of a near complete stranger, that’s really gonna make your images connect.
This is important.