Image format settings

My project i am starting is getting very large mainly due to my image format settings I have started very large and uncompressed in photoshop in the TIFF format.

Are there any guidelines or recommendations as for what format and compression to use for your build version to maximize size to quality while keeping features like transparency in your images.
Specifically i am planning to release for Retina 2048x1536.

 

In the scene window, use "Texture" and "Mipmaps" mode. You will see your texture show in blue and red color. Blue means the resolution is too low for the current window resolution. Red means too high.

 

Thank you for that tip. I didnt know that feature was available.
I have made the image sprites the correct resolutions before importing into the game my question is more in regards to image file compression for best size to quality.

 

The import format does not matter, Unity stores the images in a format suitable for real time use. Highlight an image in the Project view and look at the Preview to see the size.

If you choose the Advanced Texture Type on the Importer, you have access to a range of settings. Most are a trade off between quality and size. You will need to test different options to see what trade-off suits you best. It isn't a one-size-fits-all option. To use the compressed options, you will need a square, power-of-2 texture.

Try to reuse textures as much as possible. That is a good way to save space.