Work the subject!
Try shooting the same thing in as many ways you can that capture different aspects about it. After you shoot look through your shoot and critique your work. Be mindful of what worked and what didn’t and why. Editing your shoot is an important part of the learning process.
Study the work of other photographers.
Find something that inspires you and pay attention to what you like and try to mimic it. Then try to make it your own by bringing in something new and different.
Familiarize yourself with photography software!
Digital software is today’s darkroom & developing an image is just as important as how you shoot it. My favorite way to digitally polish my images is through Lightroom. It’s amazing what it allows you to do to an image without exposing yourself to chemicals or wasting photo paper and developer. The preset filters are a great way to intensify the tone of the image, but you must know how to fine-tune them to make the image just so. Photoshop is also an important tool.
I suggest photographing a subject at different times of day and compare them. If you have access to professional lighting equipment try shooting your subject lit from different angles, diffusion vs. Hard lighting, etc… There are jobs just dedicated to lighting on high-end shoots, so there are no limits there if you have the budget. Really think about how the light conveys your message to the viewer.
Go with your instincts!
Make sure what you are shooting is fulfilling something for you. There is no point in shooting something you aren’t enjoying. It will show in your work! The more you are passionate about it, the more creatively you can capture it! I’ve worked with so many photographers that have talent, but take on shoots they don’t enjoy and it showed in the quality of the images. For example, I could never understand why somebody would hire a nature photographer to shoot their portraits. Somebody that isn’t a people person doesn’t take flattering photos of people no matter how much technical knowledge they have. On the other hand, if you see all people as beautiful and you have a natural talent for making a person feel good about him/herself, then portrait photography is a great niche!