I'm sure most everyone here would recommend one of THE best ring routines you could ever invest in- Garrett Thomas's Ring Thing from L&L Publishing, & is my favorite impromptu go to effect. Great thing about it is as long as you always wear a ring, you've got an excellent piece of magic at all times, & I NEVER leave home without my ring, there's just so much you could do with it. In some cases, especially if you don't have a ring, you can do it with borrowed rings!
For restaurant work, Stirring Silver by Jay Sankey where you penetrate a solid spoon through ring all impromptu is awesome.
If you like rubberband magic, than Pinnacle by Russ Niedzwieckiis is the best linking ring onto rubberband effect I've ever seen, & wear both my ring AND rubberbands, another go to effect I rely on & fun with on a daily basis, & I have even come up with my own finish that I haven't seen anyone else do that is all impromptu.
Not only are all of these great effects, they are super practical in that they are impromptu, & can be done in ANY environment all in your hands & don't need anything extra like a table for example, so perfect for walk around.