Thank you! Pardon me if I've asked this before but what software do you use? With Photoshop I advise using Hard Light and Color dodge layer modes. Hard light for light and shadows and Color dodge for "glowing" effects. I found that Color dodge works really well when you use darker saturated colors because it weakens the effect and allows for more fine tuning. Hard light is weird though... I think it darkens the image with dark values and makes it brighter with bright values. Try using Dark blues and light oranges/yellows. For nighttime/Sunset/Sunrise scenarios I usually fill the layer with the color I want the shadows to be first and then apply what I want the light to look like. It is important to get a feeling for the values you choose for this, so experimentation is a must. Also if you want atmospheric bloom effects make a new Hard light layer and use an airbrush. I think thats all. If you are not using Photoshop I am sorry for all this nonsensical blabber