One way to get good portrait lighting is to use "clamshell" lighting, and there's a way to do it without without triggering Gear Acquisition Syndrome.
It's a lighting technique that can work with all sorts of portraits. What it does is uses a light source from above and one from below to light the subject. It's a relatively soft light and does not create harsh shadows.
But you don't need an elaborate studio setup to pull it off, as Alastair Currill, an English photographer, demonstrates in this Youtube video. You can do it with one flash, a modifer to soften that light and a reflector to bounce the light back up to the subject.
You can use a speedlight for the flash, and if you don't have an umbrella, you can use the DIY softbox and light stand we talked about earlier. As for the bottom light, you can use a table with a white cover or a foam board from the local big-box or dollar store.
He also has another video demonstrating the principles behind clamshell lighting, albeit using more expensive studio gear.
