There are keyboard shortcuts for almost everything in Photoshop, including changing the opacity of a tool. To change the opacity for any tool that supports it, just press any number from 1 to 0 and the opacity will change from 10% up to 100%.
For more control over this, you can press (for example) 7 then 5 to get 75% opacity.
For more flexibility when working with rounded corners in Illustrator, you can instead of using the rounded rectangle tool, use the standard Rectangle tool and draw your base shape. After that, go to Effect > Stylize > Rounded Corners. This will be saved in the appearance panel with the bonus that you can go back and change the settings whenever you want.
This is a neat tip if you are working on a document with several text layers that you would like to select and the modify together. Just select one text layer like usual in the Layers panel. Then you right click on it and choose “Select Similar Layers” and voilá, they are all selected.
If you are zoomed out or in far in Photoshop it is very easy to go back to 100%. Just double-click on the magnifying glass icon in the toolbar (the Zoom Tool) and your canvas will be back to 100%.
When you have many layers that you want to turn on and off visibility for, it can be quite a pain. Today, I have a tip that will make this go much faster.
Click on the little eye icon as usual, however before letting go, drag up (or down) to change the visibility toggle for the layers you drag over.