First off, if you're not comfortable with your camera then you're fighting an uphill battle right from the get-go. I'm a manual shooter through and through. Nearly every setting on my camera I set myself, and I manually control flash output when using a speedlight. You may not shoot this way, which is fine, but you still need to understand your equipment and be comfortable enough to make changes on the fly. I don't mean to dissuade you from trying anything here, but if you just started making photographs a few weeks ago and think you'll try your hand at photographing strangers, you've got an extra hard row to hoe and will likely come away with fewer good shots. Nothing makes for a more terrible experience than having to fumble around to figure out how to spot meter while your subject, someone who you've just interrupted, stands there waiting on you.
Secondly, make sure you're using the right lens for the job. Sure you can shoot a portrait with any lens, but your subject will look a whole lot better if you avoid using a wide-angle lens and will be easier to connect with if you're not shooting with a very long telephoto. My preferred lens is my Nikkor 50mm 1.8. Mounted on a D7000, this gives me an effective focal length of about 75mm due to the crop factor of DX sensors, which is a good focal length that doesn't distort or flatten facial features too much and allows for a good working distance between me and the subject. As a rule of thumb, when I shoot portraits I try to keep my focal length somewhere in the 70 to 120mm range.
Knowing my gear is key to the next step in the process: dialing in your settings as much as possible before even approaching the subject. For me, when I'm walking around, I'm constantly assessing the light and making adjustments to my shutter speed and aperture as I go. This usually means that when I see someone I'd like to photograph, I'm at least in the ballpark for a good exposure.
Once I find a subject, I make pretty immediate decisions about how I'd like the final image to turn out. If I want to isolate the subject from the background, I know I need to open up the lens, so I'll dial that in, check my exposure meter and finesse the shutter speed and ISO to achieve my goal. Same process, different settings, if I want more depth of field - smaller aperture, check the meter, adjust shutter and ISO as needed, all before even asking for the photo. If I'm shooting flash, this becomes a little more complicated, but usually I'll start with my power set to around 1/8th if it's fairly light where I'm shooting, to 1/4th if it's a bit darker. With flash I'll start by underexposing the entire scene by 1 to 2 stops to capture some ambient light.
More articles that might interest you