- Select the clip.
- Alt+Left Arrow; Alt+Right Arrow.
EDIT: Colin is correct (below); my shortcuts are for slide edits. (Although it works the same as Lift & Overlay if only a single clip is involved.)
1 frame earlier: Alt+, (comma)
1 frame later: Alt+. (period)
5 frames earlier: Alt+Shift+,
5 frames later: Alt+Shift+.
You can view and modify these and many other keyboard shortcuts by going to Edit > Keyboard Customization. Also, if you hold down Shift+Ctrl when you click on Keyboard Customization, a button called ">>Clipboard" will be added to the panel that will allow you to copy all of your keyboard shortcuts to the system clipboard. If you paste them into a text document, you can then print that document for reference.
Those are the shortcuts for Slide, not Nudge. Depending on how your clips are laid out in a sequence, invoking Slide versus Nudge may not have the results one is seeking. For example, if you have clips A, B, and C laid out sequentially, and you slide Clip B earlier in the sequence, it will shorten the duration of Clip A, but lengthen the duration of Clip C. Slide basically makes the head and tail of a clip "sticky" so that frames from a preceding and proceeding clip are taken along for the ride. Nudge moves the clip, but will result in a gap either at the head or tail of the clip, depending on which direction you move. Sometimes, this is what you want, and sometimes it isn't.
Thank you very much for your promt answers!