Something that is important to note is that in photoshop the default is gamma incorrect blending. If you work on game textures, and especially for effects like

Something that is important to note is that in photoshop the default is gamma incorrect blending. If you work on game textures, and especially for effects like particles, it's important that you change the photoshop option to use gamma correct alpha blending. If you don't, you will get inconsistent results between your game engine and what you author in photoshop. This isn't as important for normal image editing because the resulting image is just being viewed directly and you just edit until it looks right.