Hey everyone I started my photography career with automotive photography and now I'm slowly getting into all kinds of photography. Let me know what needs improvement with these photo. How does one get a less grainy image with terrible light conditions?
There's really no way to avoid noise in low light scenarios. You can invest in a particular camera that has "good" low-light performance, invest in aftermarket noise reduction software (with mixed results) or, and I recommend this route, bring your own light.
A common technique for portraits on the street (with a model) is to use a speedlight off camera to fill in the subject but still 'mix' and look as though it was created by a light in the scene. In the black and white one, an off camera flash from the right would give you good lighting and appear to the eye to be from the light in the background.
Otherwise you just have to chase the light at night and put your subject right in front of or under the few good light sources you have.
Good composition though.
I am working my way through a set of Annie Leibovitz videos and one key thing for her was "it's all about the light" if you don't have natural light/usable light source, then take your own. Keep it simple, a single light and something to bounce it off - maybe a flash. Grain is coming from, probably, a very high ISO even with what looks like a relatively shallow DOF - even wide open aperture in the dark won't help. I would suggest some trawling of the web including YouTube and possible investment on some street shooting and/or portrait shooting literature. What helps me the most is just keep shooting and reflecting on what worked and what needs improvement - there is no substitute for learning by doing.
In addition to other comments/suggestions, consider getting a fast lens, like maybe a 85 f1.8 (or f1.4 if you can afford it). Currently, looks like you are shooting with a 75-300 f/4-5.6. The black and white image was at 75mm 1/30 sec, f4, ISO 3200. Had you shot it an f1.8, that could have lowered your ISO 2 stops for ISO 800. The other one was 1/80 f5 ISO 3200, the f1.8 could have shaved 3 stops of ISO to 400.
With that said, just to clarify, fast glass is no substitute for good light.