1. If you want to have your photo take up the whole screen without the distractions of all your Photoshop tools on the page, etc., here’s how.
Hit the TAB key to hide your panels. Then hit the COMMAND key (CONTROL on a Windows machine) plus the zero (0) key to make your image as large as possible. Hit the (F) key twice to make a black border around your image.
2. Hold down the SHIFT key to get a straight line or align images.
Whether you’re drawing a box or painting a line, holding down the SHIFT key while you work will force Photoshop to keep you going in a straight line. Another cool feature of the SHIFT key is using it to align images. If you want to perfectly align two images on top of each other, holding down the SHIFT key while you drag and drop will put the new image dead-center on top of the old one.
When you make a Photoshop correction, use the FADE command (EDIT>FADE) to see less of the last change you made without fading the opacity of the whole layer.