Shooting hand held on low light requires you to use high ISO, resulting in a lot of noise. I found two post processing articles that improves the quality of photos taken at high ISO. The first method was stacking under exposed photos and adding these photos to resulting in a proper exposure. The next method is taking several photos at high iso and averaging the photos to remove the noise and increase detail.
The image averaging methods allows you to shoot using the highest iso while retaining details with minimal noise. Below are the steps for image averaging.
1. Set your camera at a the highest iso to prevent blur on your pictures.
2. Shoot using burst mode and take at least 4 photos to have good image quality.
3. Open all your images in Photoshop and Stack all images. For those who aren't familiar with Photoshop you can find the image stack command on (File-Scripts-Load File into stack). Check attempt to automatically align source images.
4. Adjust the fill of each image layer on your stack. The first layer or the most bottom layer will be 100% fill/opacity. The next layer will be 100/(what number of layer) so for the second layer it would be 100/2 which is equivalent to 50% fill/opacity. Third will be 100/3 which is 33% and so on and so forth.
Single Image ISO 3200
9 images averaged at ISO 3200
Cropped single image at ISO 3200
Cropped 9 images averaged at ISO 3200
After testing this method on a couple of subjects I realized that this technique has its limit. This method can't be applied on moving subjects at low light. It won't be useful if you can't reach a shutter speed that can be shot hand held on a high iso since the shots will still be blurred.
This method can be useful on taking photos of inanimate objects on low light conditions. I will most probably use this on taking food shots on the restaurants that I visit for my food blog since most of the restaurant tend to have inadequate lighting. You can also use this on taking low light city shots or interior shots, I'm sure though if you can still be able to capture light streaks with this method.
This won't replace a good old tripod but it surely will help you on those instances where you found an interesting subject on low light situation but forgot to bring your tripod.