People are asking me to post a process of the Future Bay painting.
So basically I like to start off most things with pure values - completely greyscale. The reason I do this is to make absolutely certain that my values are correct. Sometimes you can find that colours can deceive the eye if you aren't confident with colour (like me).
Alternatively you can paint straight away with colour if you like. If you want to check on your values while you paint however, just set a layer on top of all the others, fill it with black and set its filter to 'Saturation'. When you turn this layer on it will reduce your image to greyscale, giving you a clear idea of any values problems you might be having.
The advantage to painting in colour over greyscale means that your artwork tends to come out much more vibrant and full rather than looking like you painted over a black and white photo. I am not very confident with painting straight into colour and I often don't have enough time to fix issues like that so I tend to opt for straight greyscale with some quick colour washes at the end.
IF you opt for this method I recommend the following: When you are happy with your greyscale painting and you are ready to add colour, open the levels editor and reduce your whites slider by 10 and increase your blacks slider by 10. This will decrease the over all tonal range every so slightly, decreasing the contrast that naturally comes when you add colour in the next stage. Now add a layer on top of your greyscale image, set it's filter to overlay and using big soft brushes you can start washing colour over areas to get an idea of where you want to take it. Don't be afraid to play around and if you like, use photographs from real world settings as inspiration for a nice natural looking palette.
When you are all done and dusted, try manipulating the colour balance, in my case I wasn't happy with the lime light dominating the image so I infused the shadows with a dark pinky-red.